diff --git a/src/app/commands/cmd_add_color.cpp b/src/app/commands/cmd_add_color.cpp
index 0a83c1765..78ff4e944 100644
--- a/src/app/commands/cmd_add_color.cpp
+++ b/src/app/commands/cmd_add_color.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2016-2017  David Capello
+// Copyright (C) 2016-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -17,7 +17,7 @@
 #include "app/context_access.h"
 #include "app/i18n/strings.h"
 #include "app/modules/palettes.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/color_bar.h"
 #include "app/ui/context_bar.h"
 #include "app/ui/editor/editor.h"
@@ -121,9 +121,9 @@ void AddColorCommand::onExecute(Context* ctx)
     if (document) {
       frame_t frame = writer.frame();
 
-      Transaction transaction(writer.context(), friendlyName(), ModifyDocument);
-      transaction.execute(new cmd::SetPalette(sprite, frame, newPalette));
-      transaction.commit();
+      Tx tx(writer.context(), friendlyName(), ModifyDocument);
+      tx(new cmd::SetPalette(sprite, frame, newPalette));
+      tx.commit();
     }
 
     set_current_palette(newPalette, true);
diff --git a/src/app/commands/cmd_background_from_layer.cpp b/src/app/commands/cmd_background_from_layer.cpp
index ec1cfafbf..167ec9a80 100644
--- a/src/app/commands/cmd_background_from_layer.cpp
+++ b/src/app/commands/cmd_background_from_layer.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -12,7 +12,7 @@
 #include "app/context_access.h"
 #include "app/doc_api.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/color_bar.h"
 #include "doc/layer.h"
 #include "doc/sprite.h"
@@ -53,10 +53,10 @@ void BackgroundFromLayerCommand::onExecute(Context* context)
   Doc* document(writer.document());
 
   {
-    Transaction transaction(writer.context(), "Background from Layer");
-    document->getApi(transaction).backgroundFromLayer(
+    Tx tx(writer.context(), "Background from Layer");
+    document->getApi(tx).backgroundFromLayer(
       static_cast<LayerImage*>(writer.layer()));
-    transaction.commit();
+    tx.commit();
   }
 
   update_screen_for_document(document);
diff --git a/src/app/commands/cmd_canvas_size.cpp b/src/app/commands/cmd_canvas_size.cpp
index fa4fd7907..a47a9d4f3 100644
--- a/src/app/commands/cmd_canvas_size.cpp
+++ b/src/app/commands/cmd_canvas_size.cpp
@@ -13,7 +13,7 @@
 #include "app/doc_api.h"
 #include "app/modules/editors.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/button_set.h"
 #include "app/ui/color_bar.h"
 #include "app/ui/editor/editor.h"
@@ -331,14 +331,14 @@ void CanvasSizeCommand::onExecute(Context* context)
     ContextWriter writer(reader);
     Doc* document = writer.document();
     Sprite* sprite = writer.sprite();
-    Transaction transaction(writer.context(), "Canvas Size");
-    DocApi api = document->getApi(transaction);
+    Tx tx(writer.context(), "Canvas Size");
+    DocApi api = document->getApi(tx);
 
     api.cropSprite(sprite,
                    gfx::Rect(x1, y1,
                              MID(1, x2-x1, DOC_SPRITE_MAX_WIDTH),
                              MID(1, y2-y1, DOC_SPRITE_MAX_HEIGHT)));
-    transaction.commit();
+    tx.commit();
 
     document->generateMaskBoundaries();
     update_screen_for_document(document);
diff --git a/src/app/commands/cmd_cel_opacity.cpp b/src/app/commands/cmd_cel_opacity.cpp
index 6dd959ef0..29aa87636 100644
--- a/src/app/commands/cmd_cel_opacity.cpp
+++ b/src/app/commands/cmd_cel_opacity.cpp
@@ -16,7 +16,7 @@
 #include "app/context_access.h"
 #include "app/i18n/strings.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/timeline/timeline.h"
 #include "doc/cel.h"
 #include "doc/cels_range.h"
@@ -72,7 +72,7 @@ void CelOpacityCommand::onExecute(Context* context)
     return;
 
   {
-    Transaction transaction(writer.context(), "Set Cel Opacity");
+    Tx tx(writer.context(), "Set Cel Opacity");
 
     // TODO the range of selected cels should be in app::Site.
     DocRange range = App::instance()->timeline()->range();
@@ -86,12 +86,12 @@ void CelOpacityCommand::onExecute(Context* context)
         if (!c->layer()->isBackground() &&
             c->layer()->isEditable() &&
             m_opacity != c->opacity()) {
-          transaction.execute(new cmd::SetCelOpacity(c, m_opacity));
+          tx(new cmd::SetCelOpacity(c, m_opacity));
         }
       }
     }
 
-    transaction.commit();
+    tx.commit();
   }
 
   update_screen_for_document(writer.document());
diff --git a/src/app/commands/cmd_cel_properties.cpp b/src/app/commands/cmd_cel_properties.cpp
index 219335069..455b8afcd 100644
--- a/src/app/commands/cmd_cel_properties.cpp
+++ b/src/app/commands/cmd_cel_properties.cpp
@@ -17,7 +17,7 @@
 #include "app/doc_event.h"
 #include "app/doc_range.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/timeline/timeline.h"
 #include "app/ui/user_data_popup.h"
 #include "app/ui_context.h"
@@ -167,7 +167,7 @@ private:
                                  m_userData != m_cel->data()->userData()))) {
       try {
         ContextWriter writer(UIContext::instance());
-        Transaction transaction(writer.context(), "Set Cel Properties");
+        Tx tx(writer.context(), "Set Cel Properties");
 
         DocRange range;
         if (m_range.enabled())
@@ -181,12 +181,12 @@ private:
         for (Cel* cel : sprite->uniqueCels(range.selectedFrames())) {
           if (range.contains(cel->layer())) {
             if (!cel->layer()->isBackground() && newOpacity != cel->opacity()) {
-              transaction.execute(new cmd::SetCelOpacity(cel, newOpacity));
+              tx(new cmd::SetCelOpacity(cel, newOpacity));
             }
 
             if (m_newUserData &&
                 m_userData != cel->data()->userData()) {
-              transaction.execute(new cmd::SetUserData(cel->data(), m_userData));
+              tx(new cmd::SetUserData(cel->data(), m_userData));
 
               // Redraw timeline because the cel's user data/color
               // might have changed.
@@ -195,7 +195,7 @@ private:
           }
         }
 
-        transaction.commit();
+        tx.commit();
       }
       catch (const std::exception& e) {
         Console::showException(e);
diff --git a/src/app/commands/cmd_change_pixel_format.cpp b/src/app/commands/cmd_change_pixel_format.cpp
index 35ac3017b..111117e15 100644
--- a/src/app/commands/cmd_change_pixel_format.cpp
+++ b/src/app/commands/cmd_change_pixel_format.cpp
@@ -472,9 +472,9 @@ void ChangePixelFormatCommand::onExecute(Context* context)
         Sprite* sprite(job.sprite());
 
         if (flatten)
-          job.transaction().execute(new cmd::FlattenLayers(sprite));
+          job.tx()(new cmd::FlattenLayers(sprite));
 
-        job.transaction().execute(
+        job.tx()(
           new cmd::SetPixelFormat(
             sprite, m_format,
             m_ditheringAlgorithm,
diff --git a/src/app/commands/cmd_clear_cel.cpp b/src/app/commands/cmd_clear_cel.cpp
index 9a60a18ea..b3968cd7f 100644
--- a/src/app/commands/cmd_clear_cel.cpp
+++ b/src/app/commands/cmd_clear_cel.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -13,7 +13,7 @@
 #include "app/context_access.h"
 #include "app/doc_api.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/status_bar.h"
 #include "doc/cel.h"
 #include "doc/layer.h"
@@ -47,7 +47,7 @@ void ClearCelCommand::onExecute(Context* context)
   Doc* document(writer.document());
   bool nonEditableLayers = false;
   {
-    Transaction transaction(writer.context(), "Clear Cel");
+    Tx tx(writer.context(), "Clear Cel");
 
     const Site* site = writer.site();
     if (site->inTimeline() &&
@@ -66,18 +66,18 @@ void ClearCelCommand::onExecute(Context* context)
 
         for (frame_t frame : site->selectedFrames().reversed()) {
           if (layerImage->cel(frame))
-            document->getApi(transaction).clearCel(layerImage, frame);
+            document->getApi(tx).clearCel(layerImage, frame);
         }
       }
     }
     else if (writer.cel()) {
       if (writer.layer()->isEditableHierarchy())
-        document->getApi(transaction).clearCel(writer.cel());
+        document->getApi(tx).clearCel(writer.cel());
       else
         nonEditableLayers = true;
     }
 
-    transaction.commit();
+    tx.commit();
   }
 
   if (nonEditableLayers)
diff --git a/src/app/commands/cmd_color_quantization.cpp b/src/app/commands/cmd_color_quantization.cpp
index 554c79840..b10bb5b43 100644
--- a/src/app/commands/cmd_color_quantization.cpp
+++ b/src/app/commands/cmd_color_quantization.cpp
@@ -140,7 +140,7 @@ void ColorQuantizationCommand::onExecute(Context* context)
     }
 
     if (*curPalette != *newPalette)
-      job.transaction().execute(new cmd::SetPalette(sprite, frame, newPalette.get()));
+      job.tx()(new cmd::SetPalette(sprite, frame, newPalette.get()));
 
     set_current_palette(newPalette.get(), false);
     ui::Manager::getDefault()->invalidate();
diff --git a/src/app/commands/cmd_crop.cpp b/src/app/commands/cmd_crop.cpp
index 74217d121..0d1796ce0 100644
--- a/src/app/commands/cmd_crop.cpp
+++ b/src/app/commands/cmd_crop.cpp
@@ -12,7 +12,7 @@
 #include "app/context_access.h"
 #include "app/doc_api.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/color_bar.h"
 #include "app/util/autocrop.h"
 #include "doc/image.h"
@@ -71,9 +71,9 @@ void CropSpriteCommand::onExecute(Context* context)
     bounds = m_bounds;
 
   {
-    Transaction transaction(writer.context(), "Sprite Crop");
-    document->getApi(transaction).cropSprite(sprite, bounds);
-    transaction.commit();
+    Tx tx(writer.context(), "Sprite Crop");
+    document->getApi(tx).cropSprite(sprite, bounds);
+    tx.commit();
   }
   document->generateMaskBoundaries();
 
@@ -109,9 +109,9 @@ void AutocropSpriteCommand::onExecute(Context* context)
   Doc* document(writer.document());
   Sprite* sprite(writer.sprite());
   {
-    Transaction transaction(writer.context(), "Trim Sprite");
-    document->getApi(transaction).trimSprite(sprite);
-    transaction.commit();
+    Tx tx(writer.context(), "Trim Sprite");
+    document->getApi(tx).trimSprite(sprite);
+    tx.commit();
   }
   document->generateMaskBoundaries();
 
diff --git a/src/app/commands/cmd_deselect_mask.cpp b/src/app/commands/cmd_deselect_mask.cpp
index 838fcfaf5..685b1e933 100644
--- a/src/app/commands/cmd_deselect_mask.cpp
+++ b/src/app/commands/cmd_deselect_mask.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-42017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -12,7 +12,7 @@
 #include "app/commands/command.h"
 #include "app/context_access.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "doc/mask.h"
 #include "doc/sprite.h"
 
@@ -44,9 +44,9 @@ void DeselectMaskCommand::onExecute(Context* context)
   ContextWriter writer(context);
   Doc* document(writer.document());
   {
-    Transaction transaction(writer.context(), "Deselect", DoesntModifyDocument);
-    transaction.execute(new cmd::DeselectMask(document));
-    transaction.commit();
+    Tx tx(writer.context(), "Deselect", DoesntModifyDocument);
+    tx(new cmd::DeselectMask(document));
+    tx.commit();
   }
   document->generateMaskBoundaries();
   update_screen_for_document(document);
diff --git a/src/app/commands/cmd_duplicate_layer.cpp b/src/app/commands/cmd_duplicate_layer.cpp
index a834c38c9..683185f4e 100644
--- a/src/app/commands/cmd_duplicate_layer.cpp
+++ b/src/app/commands/cmd_duplicate_layer.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -16,7 +16,7 @@
 #include "app/doc_api.h"
 #include "app/modules/editors.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/editor/editor.h"
 #include "doc/layer.h"
 #include "doc/sprite.h"
@@ -51,13 +51,13 @@ void DuplicateLayerCommand::onExecute(Context* context)
   Doc* document = writer.document();
 
   {
-    Transaction transaction(writer.context(), "Layer Duplication");
+    Tx tx(writer.context(), "Layer Duplication");
     LayerImage* sourceLayer = static_cast<LayerImage*>(writer.layer());
-    DocApi api = document->getApi(transaction);
+    DocApi api = document->getApi(tx);
     api.duplicateLayerAfter(sourceLayer,
                             sourceLayer->parent(),
                             sourceLayer);
-    transaction.commit();
+    tx.commit();
   }
 
   update_screen_for_document(document);
diff --git a/src/app/commands/cmd_fill_and_stroke.cpp b/src/app/commands/cmd_fill_and_stroke.cpp
index 5e3ed1557..c10892858 100644
--- a/src/app/commands/cmd_fill_and_stroke.cpp
+++ b/src/app/commands/cmd_fill_and_stroke.cpp
@@ -16,7 +16,7 @@
 #include "app/context_access.h"
 #include "app/modules/editors.h"
 #include "app/pref/preferences.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/editor/editor.h"
 #include "app/util/expand_cel_canvas.h"
 #include "doc/algorithm/fill_selection.h"
@@ -77,11 +77,11 @@ void FillCommand::onExecute(Context* ctx)
   app::Color color = pref.colorBar.fgColor();
 
   {
-    Transaction transaction(writer.context(), "Fill Selection with Foreground Color");
+    Tx tx(writer.context(), "Fill Selection with Foreground Color");
     {
       ExpandCelCanvas expand(
         site, layer,
-        TiledMode::NONE, transaction,
+        TiledMode::NONE, tx,
         ExpandCelCanvas::None);
 
       gfx::Region rgn(sprite->bounds() |
@@ -115,9 +115,9 @@ void FillCommand::onExecute(Context* ctx)
     // If the cel wasn't deleted by cmd::ClearMask, we trim it.
     Cel* cel = ctx->activeSite().cel();
     if (cel && layer->isTransparent())
-      transaction.execute(new cmd::TrimCel(cel));
+      tx(new cmd::TrimCel(cel));
 
-    transaction.commit();
+    tx.commit();
   }
 
   doc->notifyGeneralUpdate();
diff --git a/src/app/commands/cmd_flatten_layers.cpp b/src/app/commands/cmd_flatten_layers.cpp
index cfe8fef31..49a8d6d26 100644
--- a/src/app/commands/cmd_flatten_layers.cpp
+++ b/src/app/commands/cmd_flatten_layers.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -12,7 +12,7 @@
 #include "app/commands/command.h"
 #include "app/context_access.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/color_bar.h"
 #include "doc/sprite.h"
 
@@ -43,9 +43,9 @@ void FlattenLayersCommand::onExecute(Context* context)
   ContextWriter writer(context);
   Sprite* sprite = writer.sprite();
   {
-    Transaction transaction(writer.context(), "Flatten Layers");
-    transaction.execute(new cmd::FlattenLayers(sprite));
-    transaction.commit();
+    Tx tx(writer.context(), "Flatten Layers");
+    tx(new cmd::FlattenLayers(sprite));
+    tx.commit();
   }
   update_screen_for_document(writer.document());
 }
diff --git a/src/app/commands/cmd_flip.cpp b/src/app/commands/cmd_flip.cpp
index dd29e4ce8..10031b2fa 100644
--- a/src/app/commands/cmd_flip.cpp
+++ b/src/app/commands/cmd_flip.cpp
@@ -24,7 +24,7 @@
 #include "app/modules/editors.h"
 #include "app/modules/gui.h"
 #include "app/tools/tool_box.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/editor/moving_pixels_state.h"
 #include "app/ui/status_bar.h"
@@ -111,8 +111,8 @@ void FlipCommand::onExecute(Context* context)
   ContextWriter writer(context);
   Doc* document = writer.document();
   Sprite* sprite = writer.sprite();
-  Transaction transaction(writer.context(), friendlyName());
-  DocApi api = document->getApi(transaction);
+  Tx tx(writer.context(), friendlyName());
+  DocApi api = document->getApi(tx);
 
   Mask* mask = document->mask();
   if (m_flipMask && document->isMaskVisible()) {
@@ -141,12 +141,12 @@ void FlipCommand::onExecute(Context* context)
           continue;
 
         if (mask->bitmap() && !mask->isRectangular())
-          transaction.execute(new cmd::FlipMaskedCel(cel, m_flipType));
+          tx(new cmd::FlipMaskedCel(cel, m_flipType));
         else
           api.flipImage(image, flipBounds, m_flipType);
 
         if (cel->layer()->isTransparent())
-          transaction.execute(new cmd::TrimCel(cel));
+          tx(new cmd::TrimCel(cel));
       }
       // When the mask is bigger than the cel bounds, we have to
       // expand the cel, make the flip, and shrink it again.
@@ -157,7 +157,7 @@ void FlipCommand::onExecute(Context* context)
 
         ExpandCelCanvas expand(
           site, cel->layer(),
-          TiledMode::NONE, transaction,
+          TiledMode::NONE, tx,
           ExpandCelCanvas::None);
 
         expand.validateDestCanvas(gfx::Region(flipBounds));
@@ -188,7 +188,7 @@ void FlipCommand::onExecute(Context* context)
         if (m_flipType == doc::algorithm::FlipVertical)
           bounds.y = sprite->height() - bounds.h - bounds.y;
 
-        transaction.execute(new cmd::SetCelBoundsF(cel, bounds));
+        tx(new cmd::SetCelBoundsF(cel, bounds));
       }
       else {
         api.setCelPosition
@@ -208,11 +208,11 @@ void FlipCommand::onExecute(Context* context)
   // Flip the mask.
   Image* maskBitmap = mask->bitmap();
   if (maskBitmap) {
-    transaction.execute(new cmd::FlipMask(document, m_flipType));
+    tx(new cmd::FlipMask(document, m_flipType));
 
     // Flip the mask position because the
     if (!m_flipMask)
-      transaction.execute(
+      tx(
         new cmd::SetMaskPosition(
           document,
           gfx::Point(
@@ -226,7 +226,7 @@ void FlipCommand::onExecute(Context* context)
     document->generateMaskBoundaries();
   }
 
-  transaction.commit();
+  tx.commit();
   update_screen_for_document(document);
 }
 
diff --git a/src/app/commands/cmd_frame_properties.cpp b/src/app/commands/cmd_frame_properties.cpp
index eaee1bcb7..f0c1ae743 100644
--- a/src/app/commands/cmd_frame_properties.cpp
+++ b/src/app/commands/cmd_frame_properties.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -15,7 +15,7 @@
 #include "app/context_access.h"
 #include "app/doc_api.h"
 #include "app/pref/preferences.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "base/convert_to.h"
 #include "doc/sprite.h"
 #include "ui/ui.h"
@@ -128,13 +128,13 @@ void FramePropertiesCommand::onExecute(Context* context)
     int newMsecs = window.frlen()->textInt();
 
     ContextWriter writer(reader);
-    Transaction transaction(writer.context(), "Frame Duration");
-    DocApi api = writer.document()->getApi(transaction);
+    Tx tx(writer.context(), "Frame Duration");
+    DocApi api = writer.document()->getApi(tx);
 
     for (frame_t frame : selFrames)
       api.setFrameDuration(writer.sprite(), frame, newMsecs);
 
-    transaction.commit();
+    tx.commit();
   }
 }
 
diff --git a/src/app/commands/cmd_frame_tag_properties.cpp b/src/app/commands/cmd_frame_tag_properties.cpp
index 5f431d01a..838071a71 100644
--- a/src/app/commands/cmd_frame_tag_properties.cpp
+++ b/src/app/commands/cmd_frame_tag_properties.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -17,7 +17,7 @@
 #include "app/commands/params.h"
 #include "app/context_access.h"
 #include "app/loop_tag.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/frame_tag_window.h"
 #include "base/convert_to.h"
 #include "doc/anidir.h"
@@ -87,29 +87,29 @@ void FrameTagPropertiesCommand::onExecute(Context* context)
     return;
 
   ContextWriter writer(reader);
-  Transaction transaction(writer.context(), "Change Frame Tag Properties");
+  Tx tx(writer.context(), "Change Frame Tag Properties");
   FrameTag* tag = const_cast<FrameTag*>(foundTag);
 
   std::string name = window.nameValue();
   if (tag->name() != name)
-    transaction.execute(new cmd::SetFrameTagName(tag, name));
+    tx(new cmd::SetFrameTagName(tag, name));
 
   doc::frame_t from, to;
   window.rangeValue(from, to);
   if (tag->fromFrame() != from ||
       tag->toFrame() != to) {
-    transaction.execute(new cmd::SetFrameTagRange(tag, from, to));
+    tx(new cmd::SetFrameTagRange(tag, from, to));
   }
 
   doc::color_t docColor = window.colorValue();
   if (tag->color() != docColor)
-    transaction.execute(new cmd::SetFrameTagColor(tag, docColor));
+    tx(new cmd::SetFrameTagColor(tag, docColor));
 
   doc::AniDir anidir = window.aniDirValue();
   if (tag->aniDir() != anidir)
-    transaction.execute(new cmd::SetFrameTagAniDir(tag, anidir));
+    tx(new cmd::SetFrameTagAniDir(tag, anidir));
 
-  transaction.commit();
+  tx.commit();
 }
 
 Command* CommandFactory::createFrameTagPropertiesCommand()
diff --git a/src/app/commands/cmd_import_sprite_sheet.cpp b/src/app/commands/cmd_import_sprite_sheet.cpp
index 7848df49a..06d837de2 100644
--- a/src/app/commands/cmd_import_sprite_sheet.cpp
+++ b/src/app/commands/cmd_import_sprite_sheet.cpp
@@ -21,7 +21,7 @@
 #include "app/modules/gui.h"
 #include "app/modules/palettes.h"
 #include "app/pref/preferences.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/drop_down_button.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/editor/editor_decorator.h"
@@ -385,8 +385,8 @@ void ImportSpriteSheetCommand::onExecute(Context* context)
     // The following steps modify the sprite, so we wrap all
     // operations in a undo-transaction.
     ContextWriter writer(context);
-    Transaction transaction(writer.context(), "Import Sprite Sheet", ModifyDocument);
-    DocApi api = document->getApi(transaction);
+    Tx tx(writer.context(), "Import Sprite Sheet", ModifyDocument);
+    DocApi api = document->getApi(tx);
 
     // Add the layer in the sprite.
     LayerImage* resultLayer = api.newLayer(sprite->root(), "Sprite Sheet");
@@ -416,7 +416,7 @@ void ImportSpriteSheetCommand::onExecute(Context* context)
     // Set the size of the sprite to the tile size.
     api.setSpriteSize(sprite, frameBounds.w, frameBounds.h);
 
-    transaction.commit();
+    tx.commit();
 
     ASSERT(docPref);
     if (docPref) {
diff --git a/src/app/commands/cmd_invert_mask.cpp b/src/app/commands/cmd_invert_mask.cpp
index 4478e0cea..f8799f6a3 100644
--- a/src/app/commands/cmd_invert_mask.cpp
+++ b/src/app/commands/cmd_invert_mask.cpp
@@ -13,7 +13,7 @@
 #include "app/commands/commands.h"
 #include "app/context_access.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "doc/image.h"
 #include "doc/mask.h"
 #include "doc/primitives.h"
@@ -93,9 +93,9 @@ void InvertMaskCommand::onExecute(Context* context)
     mask->intersect(sprite->bounds());
 
     // Set the new mask
-    Transaction transaction(writer.context(), "Mask Invert", DoesntModifyDocument);
-    transaction.execute(new cmd::SetMask(document, mask.get()));
-    transaction.commit();
+    Tx tx(writer.context(), "Mask Invert", DoesntModifyDocument);
+    tx(new cmd::SetMask(document, mask.get()));
+    tx.commit();
 
     document->generateMaskBoundaries();
     update_screen_for_document(document);
diff --git a/src/app/commands/cmd_layer_from_background.cpp b/src/app/commands/cmd_layer_from_background.cpp
index 17fbefe90..9463bb99a 100644
--- a/src/app/commands/cmd_layer_from_background.cpp
+++ b/src/app/commands/cmd_layer_from_background.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -12,7 +12,7 @@
 #include "app/context_access.h"
 #include "app/doc_api.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "doc/layer.h"
 #include "doc/sprite.h"
 #include "ui/ui.h"
@@ -52,9 +52,9 @@ void LayerFromBackgroundCommand::onExecute(Context* context)
   ContextWriter writer(context);
   Doc* document(writer.document());
   {
-    Transaction transaction(writer.context(), "Layer from Background");
-    document->getApi(transaction).layerFromBackground(writer.layer());
-    transaction.commit();
+    Tx tx(writer.context(), "Layer from Background");
+    document->getApi(tx).layerFromBackground(writer.layer());
+    tx.commit();
   }
   update_screen_for_document(document);
 }
diff --git a/src/app/commands/cmd_layer_opacity.cpp b/src/app/commands/cmd_layer_opacity.cpp
index e4c4b6aba..9d3e90d03 100644
--- a/src/app/commands/cmd_layer_opacity.cpp
+++ b/src/app/commands/cmd_layer_opacity.cpp
@@ -16,7 +16,7 @@
 #include "app/context_access.h"
 #include "app/i18n/strings.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/timeline/timeline.h"
 #include "doc/layer.h"
 #include "fmt/format.h"
@@ -68,7 +68,7 @@ void LayerOpacityCommand::onExecute(Context* context)
     return;
 
   {
-    Transaction transaction(writer.context(), "Set Layer Opacity");
+    Tx tx(writer.context(), "Set Layer Opacity");
 
     // TODO the range of selected frames should be in app::Site.
     SelectedLayers selLayers;
@@ -82,11 +82,10 @@ void LayerOpacityCommand::onExecute(Context* context)
 
     for (auto layer : selLayers) {
       if (layer->isImage())
-        transaction.execute(
-          new cmd::SetLayerOpacity(static_cast<LayerImage*>(layer), m_opacity));
+        tx(new cmd::SetLayerOpacity(static_cast<LayerImage*>(layer), m_opacity));
     }
 
-    transaction.commit();
+    tx.commit();
   }
 
   update_screen_for_document(writer.document());
diff --git a/src/app/commands/cmd_layer_properties.cpp b/src/app/commands/cmd_layer_properties.cpp
index e1dda4b2d..590eda648 100644
--- a/src/app/commands/cmd_layer_properties.cpp
+++ b/src/app/commands/cmd_layer_properties.cpp
@@ -19,7 +19,7 @@
 #include "app/doc.h"
 #include "app/doc_event.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/separator_in_view.h"
 #include "app/ui/timeline/timeline.h"
 #include "app/ui/user_data_popup.h"
@@ -223,7 +223,7 @@ private:
                                      newBlendMode != static_cast<LayerImage*>(m_layer)->blendMode()))))) {
       try {
         ContextWriter writer(UIContext::instance());
-        Transaction transaction(writer.context(), "Set Layer Properties");
+        Tx tx(writer.context(), "Set Layer Properties");
 
         DocRange range;
         if (m_range.enabled())
@@ -240,17 +240,17 @@ private:
 
         for (Layer* layer : range.selectedLayers()) {
           if (nameChanged && newName != layer->name())
-            transaction.execute(new cmd::SetLayerName(layer, newName));
+            tx(new cmd::SetLayerName(layer, newName));
 
           if (userDataChanged && m_userData != layer->userData())
-            transaction.execute(new cmd::SetUserData(layer, m_userData));
+            tx(new cmd::SetUserData(layer, m_userData));
 
           if (layer->isImage()) {
             if (opacityChanged && newOpacity != static_cast<LayerImage*>(layer)->opacity())
-              transaction.execute(new cmd::SetLayerOpacity(static_cast<LayerImage*>(layer), newOpacity));
+              tx(new cmd::SetLayerOpacity(static_cast<LayerImage*>(layer), newOpacity));
 
             if (blendModeChanged && newBlendMode != static_cast<LayerImage*>(layer)->blendMode())
-              transaction.execute(new cmd::SetLayerBlendMode(static_cast<LayerImage*>(layer), newBlendMode));
+              tx(new cmd::SetLayerBlendMode(static_cast<LayerImage*>(layer), newBlendMode));
           }
         }
 
@@ -258,7 +258,7 @@ private:
         // might have changed.
         App::instance()->timeline()->invalidate();
 
-        transaction.commit();
+        tx.commit();
       }
       catch (const std::exception& e) {
         Console::showException(e);
diff --git a/src/app/commands/cmd_link_cels.cpp b/src/app/commands/cmd_link_cels.cpp
index 364d8f1e4..7c27f6e39 100644
--- a/src/app/commands/cmd_link_cels.cpp
+++ b/src/app/commands/cmd_link_cels.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -13,7 +13,7 @@
 #include "app/commands/command.h"
 #include "app/context_access.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/status_bar.h"
 #include "doc/cel.h"
 #include "doc/layer.h"
@@ -57,7 +57,7 @@ void LinkCelsCommand::onExecute(Context* context)
     if (!site.inTimeline())
       return;
 
-    Transaction transaction(writer.context(), friendlyName());
+    Tx tx(writer.context(), friendlyName());
 
     for (Layer* layer : site.selectedLayers()) {
       if (!layer->isImage())
@@ -76,7 +76,7 @@ void LinkCelsCommand::onExecute(Context* context)
         Cel* cel = layerImage->cel(frame);
         if (cel) {
           for (++it; it != end; ++it) {
-            transaction.execute(
+            tx(
               new cmd::CopyCel(
                 layerImage, cel->frame(),
                 layerImage, *it,
@@ -87,7 +87,7 @@ void LinkCelsCommand::onExecute(Context* context)
       }
     }
 
-    transaction.commit();
+    tx.commit();
   }
 
   if (nonEditableLayers)
diff --git a/src/app/commands/cmd_load_mask.cpp b/src/app/commands/cmd_load_mask.cpp
index 412b7a29e..55a6d2f98 100644
--- a/src/app/commands/cmd_load_mask.cpp
+++ b/src/app/commands/cmd_load_mask.cpp
@@ -15,7 +15,7 @@
 #include "app/file_selector.h"
 #include "app/i18n/strings.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/util/msk_file.h"
 #include "doc/mask.h"
 #include "doc/sprite.h"
@@ -77,9 +77,9 @@ void LoadMaskCommand::onExecute(Context* context)
   {
     ContextWriter writer(reader);
     Doc* document = writer.document();
-    Transaction transaction(writer.context(), "Mask Load", DoesntModifyDocument);
-    transaction.execute(new cmd::SetMask(document, mask.get()));
-    transaction.commit();
+    Tx tx(writer.context(), "Mask Load", DoesntModifyDocument);
+    tx(new cmd::SetMask(document, mask.get()));
+    tx.commit();
 
     document->generateMaskBoundaries();
     update_screen_for_document(document);
diff --git a/src/app/commands/cmd_mask_all.cpp b/src/app/commands/cmd_mask_all.cpp
index e1183f9da..bbf457c2e 100644
--- a/src/app/commands/cmd_mask_all.cpp
+++ b/src/app/commands/cmd_mask_all.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -12,7 +12,7 @@
 #include "app/commands/command.h"
 #include "app/context_access.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "doc/mask.h"
 #include "doc/sprite.h"
 #include "app/pref/preferences.h"
@@ -49,9 +49,9 @@ void MaskAllCommand::onExecute(Context* context)
   Mask newMask;
   newMask.replace(sprite->bounds());
 
-  Transaction transaction(writer.context(), "Select All", DoesntModifyDocument);
-  transaction.execute(new cmd::SetMask(document, &newMask));
-  transaction.commit();
+  Tx tx(writer.context(), "Select All", DoesntModifyDocument);
+  tx(new cmd::SetMask(document, &newMask));
+  tx.commit();
 
   document->resetTransformation();
   document->generateMaskBoundaries();
diff --git a/src/app/commands/cmd_mask_by_color.cpp b/src/app/commands/cmd_mask_by_color.cpp
index 569c5d1d2..e568501ff 100644
--- a/src/app/commands/cmd_mask_by_color.cpp
+++ b/src/app/commands/cmd_mask_by_color.cpp
@@ -19,7 +19,7 @@
 #include "app/ini_file.h"
 #include "app/modules/editors.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/color_bar.h"
 #include "app/ui/color_button.h"
 #include "base/bind.h"
@@ -159,10 +159,10 @@ void MaskByColorCommand::onExecute(Context* context)
   Doc* document(writer.document());
 
   if (apply) {
-    Transaction transaction(writer.context(), "Mask by Color", DoesntModifyDocument);
+    Tx tx(writer.context(), "Mask by Color", DoesntModifyDocument);
     std::unique_ptr<Mask> mask(generateMask(sprite, image, xpos, ypos));
-    transaction.execute(new cmd::SetMask(document, mask.get()));
-    transaction.commit();
+    tx(new cmd::SetMask(document, mask.get()));
+    tx.commit();
 
     set_config_color("MaskColor", "Color", m_buttonColor->getColor());
     set_config_int("MaskColor", "Tolerance", m_sliderTolerance->getValue());
diff --git a/src/app/commands/cmd_mask_content.cpp b/src/app/commands/cmd_mask_content.cpp
index 2a951d116..34caae197 100644
--- a/src/app/commands/cmd_mask_content.cpp
+++ b/src/app/commands/cmd_mask_content.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -17,7 +17,7 @@
 #include "app/modules/editors.h"
 #include "app/modules/gui.h"
 #include "app/tools/tool_box.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/toolbar.h"
 #include "doc/algorithm/shrink_bounds.h"
@@ -82,9 +82,9 @@ void MaskContentCommand::onExecute(Context* context)
       newMask.replace(cel->bounds());
     }
 
-    Transaction transaction(writer.context(), "Select Content", DoesntModifyDocument);
-    transaction.execute(new cmd::SetMask(document, &newMask));
-    transaction.commit();
+    Tx tx(writer.context(), "Select Content", DoesntModifyDocument);
+    tx(new cmd::SetMask(document, &newMask));
+    tx.commit();
 
     document->resetTransformation();
     document->generateMaskBoundaries();
diff --git a/src/app/commands/cmd_merge_down_layer.cpp b/src/app/commands/cmd_merge_down_layer.cpp
index e53355530..24f6601e1 100644
--- a/src/app/commands/cmd_merge_down_layer.cpp
+++ b/src/app/commands/cmd_merge_down_layer.cpp
@@ -18,7 +18,7 @@
 #include "app/doc.h"
 #include "app/doc_api.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "doc/blend_internals.h"
 #include "doc/cel.h"
 #include "doc/image.h"
@@ -68,7 +68,7 @@ void MergeDownLayerCommand::onExecute(Context* context)
   ContextWriter writer(context);
   Doc* document(writer.document());
   Sprite* sprite(writer.sprite());
-  Transaction transaction(writer.context(), "Merge Down Layer", ModifyDocument);
+  Tx tx(writer.context(), "Merge Down Layer", ModifyDocument);
   LayerImage* src_layer = static_cast<LayerImage*>(writer.layer());
   Layer* dst_layer = src_layer->getPrevious();
 
@@ -106,7 +106,7 @@ void MergeDownLayerCommand::onExecute(Context* context)
         dst_cel->setPosition(src_cel->x(), src_cel->y());
         dst_cel->setOpacity(opacity);
 
-        transaction.execute(new cmd::AddCel(dst_layer, dst_cel));
+        tx(new cmd::AddCel(dst_layer, dst_cel));
       }
       // With destination
       else {
@@ -138,22 +138,22 @@ void MergeDownLayerCommand::onExecute(Context* context)
           opacity,
           src_layer->blendMode());
 
-        transaction.execute(new cmd::SetCelPosition(dst_cel,
+        tx(new cmd::SetCelPosition(dst_cel,
             bounds.x, bounds.y));
 
         if (dst_cel->links())
-          transaction.execute(new cmd::UnlinkCel(dst_cel));
+          tx(new cmd::UnlinkCel(dst_cel));
 
-        transaction.execute(new cmd::ReplaceImage(sprite,
+        tx(new cmd::ReplaceImage(sprite,
             dst_cel->imageRef(), new_image));
       }
     }
   }
 
   document->notifyLayerMergedDown(src_layer, dst_layer);
-  document->getApi(transaction).removeLayer(src_layer); // src_layer is deleted inside removeLayer()
+  document->getApi(tx).removeLayer(src_layer); // src_layer is deleted inside removeLayer()
 
-  transaction.commit();
+  tx.commit();
   update_screen_for_document(document);
 }
 
diff --git a/src/app/commands/cmd_modify_selection.cpp b/src/app/commands/cmd_modify_selection.cpp
index b1106ff98..edba17b6b 100644
--- a/src/app/commands/cmd_modify_selection.cpp
+++ b/src/app/commands/cmd_modify_selection.cpp
@@ -16,7 +16,7 @@
 #include "app/i18n/strings.h"
 #include "app/modules/gui.h"
 #include "app/pref/preferences.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "base/convert_to.h"
 #include "doc/algorithm/modify_selection.h"
 #include "doc/brush_type.h"
@@ -138,11 +138,11 @@ void ModifySelectionCommand::onExecute(Context* context)
   }
 
   // Set the new mask
-  Transaction transaction(writer.context(),
-                          friendlyName(),
-                          DoesntModifyDocument);
-  transaction.execute(new cmd::SetMask(document, mask.get()));
-  transaction.commit();
+  Tx tx(writer.context(),
+        friendlyName(),
+        DoesntModifyDocument);
+  tx(new cmd::SetMask(document, mask.get()));
+  tx.commit();
 
   document->generateMaskBoundaries();
   update_screen_for_document(document);
diff --git a/src/app/commands/cmd_move_mask.cpp b/src/app/commands/cmd_move_mask.cpp
index fb163ad7d..2d66886f7 100644
--- a/src/app/commands/cmd_move_mask.cpp
+++ b/src/app/commands/cmd_move_mask.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -19,7 +19,7 @@
 #include "app/modules/editors.h"
 #include "app/modules/gui.h"
 #include "app/pref/preferences.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/doc_view.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui_context.h"
@@ -82,10 +82,10 @@ void MoveMaskCommand::onExecute(Context* context)
       ContextWriter writer(context);
       Doc* document(writer.document());
       {
-        Transaction transaction(writer.context(), "Move Selection", DoesntModifyDocument);
+        Tx tx(writer.context(), "Move Selection", DoesntModifyDocument);
         gfx::Point pt = document->mask()->bounds().origin();
-        document->getApi(transaction).setMaskPosition(pt.x+delta.x, pt.y+delta.y);
-        transaction.commit();
+        document->getApi(tx).setMaskPosition(pt.x+delta.x, pt.y+delta.y);
+        tx.commit();
       }
 
       document->generateMaskBoundaries();
@@ -98,9 +98,9 @@ void MoveMaskCommand::onExecute(Context* context)
         ContextWriter writer(context);
         if (writer.cel()) {
           // Rotate content
-          Transaction transaction(writer.context(), "Shift Pixels");
-          transaction.execute(new cmd::ShiftMaskedCel(writer.cel(), delta.x, delta.y));
-          transaction.commit();
+          Tx tx(writer.context(), "Shift Pixels");
+          tx(new cmd::ShiftMaskedCel(writer.cel(), delta.x, delta.y));
+          tx.commit();
         }
         update_screen_for_document(writer.document());
       }
diff --git a/src/app/commands/cmd_new_brush.cpp b/src/app/commands/cmd_new_brush.cpp
index 24f870f32..126dfd5eb 100644
--- a/src/app/commands/cmd_new_brush.cpp
+++ b/src/app/commands/cmd_new_brush.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -18,7 +18,7 @@
 #include "app/tools/active_tool.h"
 #include "app/tools/ink.h"
 #include "app/tools/tool_box.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/context_bar.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/editor/select_box_state.h"
@@ -113,9 +113,9 @@ void NewBrushCommand::onQuickboxEnd(Editor* editor, const gfx::Rect& rect, ui::M
     try {
       ContextWriter writer(UIContext::instance(), 250);
       if (writer.cel()) {
-        Transaction transaction(writer.context(), "Clear");
-        transaction.execute(new cmd::ClearRect(writer.cel(), rect));
-        transaction.commit();
+        Tx tx(writer.context(), "Clear");
+        tx(new cmd::ClearRect(writer.cel(), rect));
+        tx.commit();
       }
     }
     catch (const std::exception& ex) {
diff --git a/src/app/commands/cmd_new_frame.cpp b/src/app/commands/cmd_new_frame.cpp
index 5304884c7..9c102bda5 100644
--- a/src/app/commands/cmd_new_frame.cpp
+++ b/src/app/commands/cmd_new_frame.cpp
@@ -17,7 +17,7 @@
 #include "app/doc_api.h"
 #include "app/i18n/strings.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/doc_view.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/main_window.h"
@@ -90,8 +90,8 @@ void NewFrameCommand::onExecute(Context* context)
   Doc* document(writer.document());
   Sprite* sprite(writer.sprite());
   {
-    Transaction transaction(writer.context(), friendlyName());
-    DocApi api = document->getApi(transaction);
+    Tx tx(writer.context(), friendlyName());
+    DocApi api = document->getApi(tx);
 
     switch (m_content) {
 
@@ -179,7 +179,7 @@ void NewFrameCommand::onExecute(Context* context)
       }
     }
 
-    transaction.commit();
+    tx.commit();
   }
   update_screen_for_document(document);
 
diff --git a/src/app/commands/cmd_new_frame_tag.cpp b/src/app/commands/cmd_new_frame_tag.cpp
index 55b1eeda8..efded840d 100644
--- a/src/app/commands/cmd_new_frame_tag.cpp
+++ b/src/app/commands/cmd_new_frame_tag.cpp
@@ -13,7 +13,7 @@
 #include "app/commands/command.h"
 #include "app/context.h"
 #include "app/context_access.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/frame_tag_window.h"
 #include "app/ui/timeline/timeline.h"
 #include "doc/frame_tag.h"
@@ -73,10 +73,10 @@ void NewFrameTagCommand::onExecute(Context* context)
 
   {
     ContextWriter writer(reader);
-    Transaction transaction(writer.context(), "New Frames Tag");
-    transaction.execute(new cmd::AddFrameTag(writer.sprite(), frameTag.get()));
+    Tx tx(writer.context(), "New Frames Tag");
+    tx(new cmd::AddFrameTag(writer.sprite(), frameTag.get()));
     frameTag.release();
-    transaction.commit();
+    tx.commit();
   }
 
   App::instance()->timeline()->invalidate();
diff --git a/src/app/commands/cmd_new_layer.cpp b/src/app/commands/cmd_new_layer.cpp
index a48fe9ae4..8703c8acd 100644
--- a/src/app/commands/cmd_new_layer.cpp
+++ b/src/app/commands/cmd_new_layer.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -18,7 +18,7 @@
 #include "app/find_widget.h"
 #include "app/load_widget.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/main_window.h"
 #include "app/ui/status_bar.h"
 #include "app/ui_context.h"
@@ -177,10 +177,10 @@ void NewLayerCommand::onExecute(Context* context)
 
   Layer* layer = nullptr;
   {
-    Transaction transaction(
+    Tx tx(
       writer.context(),
       std::string("New ") + layerPrefix());
-    DocApi api = document->getApi(transaction);
+    DocApi api = document->getApi(tx);
     bool afterBackground = false;
 
     switch (m_type) {
@@ -236,7 +236,7 @@ void NewLayerCommand::onExecute(Context* context)
 
       if (sameParents == selLayers.size()) {
         for (Layer* newChild : selLayers.toLayerList()) {
-          transaction.execute(
+          tx(
             new cmd::MoveLayer(newChild, layer,
                                static_cast<LayerGroup*>(layer)->lastLayer()));
         }
@@ -311,7 +311,7 @@ void NewLayerCommand::onExecute(Context* context)
       }
     }
 
-    transaction.commit();
+    tx.commit();
   }
   update_screen_for_document(document);
 
diff --git a/src/app/commands/cmd_palette_size.cpp b/src/app/commands/cmd_palette_size.cpp
index 688eb8b43..098808537 100644
--- a/src/app/commands/cmd_palette_size.cpp
+++ b/src/app/commands/cmd_palette_size.cpp
@@ -13,7 +13,7 @@
 #include "app/commands/params.h"
 #include "app/context_access.h"
 #include "app/modules/palettes.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "doc/palette.h"
 #include "doc/sprite.h"
 #include "ui/manager.h"
@@ -65,9 +65,9 @@ void PaletteSizeCommand::onExecute(Context* context)
     palette.resize(MID(1, ncolors, std::numeric_limits<int>::max()));
 
     ContextWriter writer(reader);
-    Transaction transaction(context, "Palette Size", ModifyDocument);
-    transaction.execute(new cmd::SetPalette(writer.sprite(), frame, &palette));
-    transaction.commit();
+    Tx tx(context, "Palette Size", ModifyDocument);
+    tx(new cmd::SetPalette(writer.sprite(), frame, &palette));
+    tx.commit();
 
     set_current_palette(&palette, false);
     ui::Manager::getDefault()->invalidate();
diff --git a/src/app/commands/cmd_remove_frame.cpp b/src/app/commands/cmd_remove_frame.cpp
index 4411070d6..cb56cf30e 100644
--- a/src/app/commands/cmd_remove_frame.cpp
+++ b/src/app/commands/cmd_remove_frame.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -13,7 +13,7 @@
 #include "app/context_access.h"
 #include "app/doc_api.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "doc/sprite.h"
 #include "ui/ui.h"
 
@@ -49,8 +49,8 @@ void RemoveFrameCommand::onExecute(Context* context)
   Doc* document(writer.document());
   Sprite* sprite(writer.sprite());
   {
-    Transaction transaction(writer.context(), "Remove Frame");
-    DocApi api = document->getApi(transaction);
+    Tx tx(writer.context(), "Remove Frame");
+    DocApi api = document->getApi(tx);
     const Site* site = writer.site();
     if (site->inTimeline() &&
         !site->selectedFrames().empty()) {
@@ -62,7 +62,7 @@ void RemoveFrameCommand::onExecute(Context* context)
       api.removeFrame(sprite, writer.frame());
     }
 
-    transaction.commit();
+    tx.commit();
   }
   update_screen_for_document(document);
 }
diff --git a/src/app/commands/cmd_remove_frame_tag.cpp b/src/app/commands/cmd_remove_frame_tag.cpp
index 9d2b1d1fe..d07219c6d 100644
--- a/src/app/commands/cmd_remove_frame_tag.cpp
+++ b/src/app/commands/cmd_remove_frame_tag.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -15,7 +15,7 @@
 #include "app/context.h"
 #include "app/context_access.h"
 #include "app/loop_tag.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/timeline/timeline.h"
 #include "base/convert_to.h"
 #include "doc/frame_tag.h"
@@ -77,9 +77,9 @@ void RemoveFrameTagCommand::onExecute(Context* context)
   if (!foundTag)
     return;
 
-  Transaction transaction(writer.context(), "Remove Frame Tag");
-  transaction.execute(new cmd::RemoveFrameTag(sprite, foundTag));
-  transaction.commit();
+  Tx tx(writer.context(), "Remove Frame Tag");
+  tx(new cmd::RemoveFrameTag(sprite, foundTag));
+  tx.commit();
 
   App::instance()->timeline()->invalidate();
 }
diff --git a/src/app/commands/cmd_remove_layer.cpp b/src/app/commands/cmd_remove_layer.cpp
index e20c27924..57d67d2dd 100644
--- a/src/app/commands/cmd_remove_layer.cpp
+++ b/src/app/commands/cmd_remove_layer.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -14,7 +14,7 @@
 #include "app/doc_api.h"
 #include "app/i18n/strings.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/status_bar.h"
 #include "doc/layer.h"
 #include "doc/sprite.h"
@@ -52,8 +52,8 @@ void RemoveLayerCommand::onExecute(Context* context)
   Doc* document(writer.document());
   Sprite* sprite(writer.sprite());
   {
-    Transaction transaction(writer.context(), "Remove Layer");
-    DocApi api = document->getApi(transaction);
+    Tx tx(writer.context(), "Remove Layer");
+    DocApi api = document->getApi(tx);
 
     const Site* site = writer.site();
     if (site->inTimeline() &&
@@ -87,7 +87,7 @@ void RemoveLayerCommand::onExecute(Context* context)
       api.removeLayer(layer);
     }
 
-    transaction.commit();
+    tx.commit();
   }
   update_screen_for_document(document);
 
diff --git a/src/app/commands/cmd_remove_slice.cpp b/src/app/commands/cmd_remove_slice.cpp
index c4d1a687e..370e31b20 100644
--- a/src/app/commands/cmd_remove_slice.cpp
+++ b/src/app/commands/cmd_remove_slice.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2017  David Capello
+// Copyright (C) 2017-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -15,7 +15,7 @@
 #include "app/context_access.h"
 #include "app/modules/gui.h"
 #include "app/ui/status_bar.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "base/convert_to.h"
 #include "doc/slice.h"
 #include "doc/sprite.h"
@@ -83,16 +83,16 @@ void RemoveSliceCommand::onExecute(Context* context)
     ContextWriter writer(reader, 500);
     Doc* document(writer.document());
     Sprite* sprite(writer.sprite());
-    Transaction transaction(writer.context(), "Remove Slice");
+    Tx tx(writer.context(), "Remove Slice");
     Slice* slice = const_cast<Slice*>(foundSlice);
 
     if (slice->size() > 1) {
-      transaction.execute(new cmd::SetSliceKey(slice, frame, SliceKey()));
+      tx(new cmd::SetSliceKey(slice, frame, SliceKey()));
     }
     else {
-      transaction.execute(new cmd::RemoveSlice(sprite, slice));
+      tx(new cmd::RemoveSlice(sprite, slice));
     }
-    transaction.commit();
+    tx.commit();
     document->notifyGeneralUpdate();
   }
 
diff --git a/src/app/commands/cmd_reselect_mask.cpp b/src/app/commands/cmd_reselect_mask.cpp
index 8d03be07f..931e83ce8 100644
--- a/src/app/commands/cmd_reselect_mask.cpp
+++ b/src/app/commands/cmd_reselect_mask.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -12,7 +12,7 @@
 #include "app/commands/command.h"
 #include "app/context_access.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "doc/mask.h"
 #include "doc/sprite.h"
 
@@ -49,9 +49,9 @@ void ReselectMaskCommand::onExecute(Context* context)
   ContextWriter writer(context);
   Doc* document(writer.document());
   {
-    Transaction transaction(writer.context(), "Reselect", DoesntModifyDocument);
-    transaction.execute(new cmd::ReselectMask(document));
-    transaction.commit();
+    Tx tx(writer.context(), "Reselect", DoesntModifyDocument);
+    tx(new cmd::ReselectMask(document));
+    tx.commit();
   }
 
   document->generateMaskBoundaries();
diff --git a/src/app/commands/cmd_rotate.cpp b/src/app/commands/cmd_rotate.cpp
index 10db653bd..e0a1283a7 100644
--- a/src/app/commands/cmd_rotate.cpp
+++ b/src/app/commands/cmd_rotate.cpp
@@ -20,7 +20,7 @@
 #include "app/modules/gui.h"
 #include "app/sprite_job.h"
 #include "app/tools/tool_box.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/color_bar.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/status_bar.h"
@@ -79,7 +79,7 @@ protected:
 
   // [working thread]
   void onJob() override {
-    DocApi api = document()->getApi(transaction());
+    DocApi api = document()->getApi(tx());
 
     // 1) Rotate cel positions
     for (Cel* cel : m_cels) {
@@ -91,7 +91,7 @@ protected:
         gfx::RectF bounds = cel->boundsF();
         rotate_rect(bounds);
         if (cel->boundsF() != bounds)
-          transaction().execute(new cmd::SetCelBoundsF(cel, bounds));
+          tx()(new cmd::SetCelBoundsF(cel, bounds));
       }
       else {
         gfx::Rect bounds = cel->bounds();
@@ -120,7 +120,7 @@ protected:
 
       // cancel all the operation?
       if (isCanceled())
-        return;        // Transaction destructor will undo all operations
+        return;        // Tx destructor will undo all operations
     }
 
     // rotate mask
diff --git a/src/app/commands/cmd_select_tile.cpp b/src/app/commands/cmd_select_tile.cpp
index 05f13a07c..8977a9178 100644
--- a/src/app/commands/cmd_select_tile.cpp
+++ b/src/app/commands/cmd_select_tile.cpp
@@ -17,7 +17,7 @@
 #include "app/modules/gui.h"
 #include "app/pref/preferences.h"
 #include "app/snap_to_grid.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/editor/editor.h"
 #include "doc/mask.h"
 #include "fmt/format.h"
@@ -93,11 +93,11 @@ void SelectTileCommand::onExecute(Context* ctx)
   }
 
   // Set the new mask
-  Transaction transaction(writer.context(),
+  Tx tx(writer.context(),
                           friendlyName(),
                           DoesntModifyDocument);
-  transaction.execute(new cmd::SetMask(doc, mask.get()));
-  transaction.commit();
+  tx(new cmd::SetMask(doc, mask.get()));
+  tx.commit();
 
   doc->generateMaskBoundaries();
   update_screen_for_document(doc);
diff --git a/src/app/commands/cmd_set_loop_section.cpp b/src/app/commands/cmd_set_loop_section.cpp
index b2335856a..eba3b1b12 100644
--- a/src/app/commands/cmd_set_loop_section.cpp
+++ b/src/app/commands/cmd_set_loop_section.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -17,7 +17,7 @@
 #include "app/commands/params.h"
 #include "app/context_access.h"
 #include "app/loop_tag.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/timeline/timeline.h"
 #include "doc/frame_tag.h"
 
@@ -108,16 +108,16 @@ void SetLoopSectionCommand::onExecute(Context* ctx)
       loopTag = create_loop_tag(begin, end);
 
       ContextWriter writer(ctx);
-      Transaction transaction(writer.context(), "Add Loop");
-      transaction.execute(new cmd::AddFrameTag(sprite, loopTag));
-      transaction.commit();
+      Tx tx(writer.context(), "Add Loop");
+      tx(new cmd::AddFrameTag(sprite, loopTag));
+      tx.commit();
     }
     else if (loopTag->fromFrame() != begin ||
              loopTag->toFrame() != end) {
       ContextWriter writer(ctx);
-      Transaction transaction(writer.context(), "Set Loop Range");
-      transaction.execute(new cmd::SetFrameTagRange(loopTag, begin, end));
-      transaction.commit();
+      Tx tx(writer.context(), "Set Loop Range");
+      tx(new cmd::SetFrameTagRange(loopTag, begin, end));
+      tx.commit();
     }
     else {
       Command* cmd = Commands::instance()->byId(CommandId::FrameTagProperties());
@@ -127,9 +127,9 @@ void SetLoopSectionCommand::onExecute(Context* ctx)
   else {
     if (loopTag) {
       ContextWriter writer(ctx);
-      Transaction transaction(writer.context(), "Remove Loop");
-      transaction.execute(new cmd::RemoveFrameTag(sprite, loopTag));
-      transaction.commit();
+      Tx tx(writer.context(), "Remove Loop");
+      tx(new cmd::RemoveFrameTag(sprite, loopTag));
+      tx.commit();
     }
   }
 
diff --git a/src/app/commands/cmd_set_palette.cpp b/src/app/commands/cmd_set_palette.cpp
index cf584ffb4..b8587878f 100644
--- a/src/app/commands/cmd_set_palette.cpp
+++ b/src/app/commands/cmd_set_palette.cpp
@@ -14,7 +14,7 @@
 #include "app/file_selector.h"
 #include "app/ini_file.h"
 #include "app/modules/palettes.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "doc/palette.h"
 #include "ui/alert.h"
 #include "ui/manager.h"
@@ -37,10 +37,10 @@ void SetPaletteCommand::onExecute(Context* context)
 
   ContextWriter writer(context);
   if (writer.document()) {
-    Transaction transaction(writer.context(), "Set Palette");
-    writer.document()->getApi(transaction)
+    Tx tx(writer.context(), "Set Palette");
+    writer.document()->getApi(tx)
       .setPalette(writer.sprite(), writer.frame(), m_palette);
-    transaction.commit();
+    tx.commit();
   }
   set_current_palette(m_palette, false);
 
diff --git a/src/app/commands/cmd_slice_properties.cpp b/src/app/commands/cmd_slice_properties.cpp
index 59f101c2c..c32f7bf2a 100644
--- a/src/app/commands/cmd_slice_properties.cpp
+++ b/src/app/commands/cmd_slice_properties.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2017  David Capello
+// Copyright (C) 2017-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -13,7 +13,7 @@
 #include "app/cmd/set_user_data.h"
 #include "app/commands/command.h"
 #include "app/context_access.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/slice_window.h"
 #include "base/convert_to.h"
 #include "doc/slice.h"
@@ -85,16 +85,16 @@ void SlicePropertiesCommand::onExecute(Context* context)
 
   {
     ContextWriter writer(reader, 500);
-    Transaction transaction(writer.context(), "Slice Properties");
+    Tx tx(writer.context(), "Slice Properties");
     Slice* slice = const_cast<Slice*>(foundSlice);
 
     std::string name = window.nameValue();
 
     if (slice->name() != name)
-      transaction.execute(new cmd::SetSliceName(slice, name));
+      tx(new cmd::SetSliceName(slice, name));
 
     if (slice->userData() != window.userDataValue())
-      transaction.execute(new cmd::SetUserData(slice, window.userDataValue()));
+      tx(new cmd::SetUserData(slice, window.userDataValue()));
 
     if (key->bounds() != window.boundsValue() ||
         key->center() != window.centerValue() ||
@@ -103,10 +103,10 @@ void SlicePropertiesCommand::onExecute(Context* context)
       newKey.setBounds(window.boundsValue());
       newKey.setCenter(window.centerValue());
       newKey.setPivot(window.pivotValue());
-      transaction.execute(new cmd::SetSliceKey(slice, frame, newKey));
+      tx(new cmd::SetSliceKey(slice, frame, newKey));
     }
 
-    transaction.commit();
+    tx.commit();
     writer.document()->notifyGeneralUpdate();
   }
 }
diff --git a/src/app/commands/cmd_sprite_properties.cpp b/src/app/commands/cmd_sprite_properties.cpp
index 39593e2d6..1b917df2b 100644
--- a/src/app/commands/cmd_sprite_properties.cpp
+++ b/src/app/commands/cmd_sprite_properties.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -14,7 +14,7 @@
 #include "app/context_access.h"
 #include "app/doc_api.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/color_button.h"
 #include "app/util/pixel_ratio.h"
 #include "base/bind.h"
@@ -136,16 +136,16 @@ void SpritePropertiesCommand::onExecute(Context* context)
 
     if (index != sprite->transparentColor() ||
         pixelRatio != sprite->pixelRatio()) {
-      Transaction transaction(writer.context(), "Change Sprite Properties");
-      DocApi api = writer.document()->getApi(transaction);
+      Tx tx(writer.context(), "Change Sprite Properties");
+      DocApi api = writer.document()->getApi(tx);
 
       if (index != sprite->transparentColor())
         api.setSpriteTransparentColor(sprite, index);
 
       if (pixelRatio != sprite->pixelRatio())
-        transaction.execute(new cmd::SetPixelRatio(sprite, pixelRatio));
+        tx(new cmd::SetPixelRatio(sprite, pixelRatio));
 
-      transaction.commit();
+      tx.commit();
 
       update_screen_for_document(writer.document());
     }
diff --git a/src/app/commands/cmd_sprite_size.cpp b/src/app/commands/cmd_sprite_size.cpp
index f7d2ff3b5..5d7bb0b8f 100644
--- a/src/app/commands/cmd_sprite_size.cpp
+++ b/src/app/commands/cmd_sprite_size.cpp
@@ -72,7 +72,7 @@ protected:
 
   // [working thread]
   void onJob() override {
-    DocApi api = writer().document()->getApi(transaction());
+    DocApi api = writer().document()->getApi(tx());
 
     int cels_count = 0;
     for (Cel* cel : sprite()->uniqueCels()) { // TODO add size() member function to CelsRange
@@ -89,7 +89,7 @@ protected:
         // Resize the cel bounds only if it's from a reference layer
         if (cel->layer()->isReference()) {
           gfx::RectF newBounds = scale_rect<double>(cel->boundsF());
-          transaction().execute(new cmd::SetCelBoundsF(cel, newBounds));
+          tx()(new cmd::SetCelBoundsF(cel, newBounds));
         }
         else {
           // Change its location
@@ -118,7 +118,7 @@ protected:
 
       // Cancel all the operation?
       if (isCanceled())
-        return;        // Transaction destructor will undo all operations
+        return;        // Tx destructor will undo all operations
     }
 
     // Resize mask
@@ -170,8 +170,7 @@ protected:
           newKey.setPivot(gfx::Point(scale_x(newKey.pivot().x),
                                      scale_y(newKey.pivot().y)));
 
-        transaction().execute(
-          new cmd::SetSliceKey(slice, k.frame(), newKey));
+        tx()(new cmd::SetSliceKey(slice, k.frame(), newKey));
       }
     }
 
diff --git a/src/app/commands/cmd_unlink_cel.cpp b/src/app/commands/cmd_unlink_cel.cpp
index 70d663991..2298cf12b 100644
--- a/src/app/commands/cmd_unlink_cel.cpp
+++ b/src/app/commands/cmd_unlink_cel.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2017  David Capello
+// Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -13,7 +13,7 @@
 #include "app/commands/command.h"
 #include "app/context_access.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/status_bar.h"
 #include "doc/cel.h"
 #include "doc/layer.h"
@@ -47,7 +47,7 @@ void UnlinkCelCommand::onExecute(Context* context)
   Doc* document(writer.document());
   bool nonEditableLayers = false;
   {
-    Transaction transaction(writer.context(), "Unlink Cel");
+    Tx tx(writer.context(), "Unlink Cel");
 
     const Site* site = writer.site();
     if (site->inTimeline() &&
@@ -66,7 +66,7 @@ void UnlinkCelCommand::onExecute(Context* context)
         for (frame_t frame : site->selectedFrames().reversed()) {
           Cel* cel = layerImage->cel(frame);
           if (cel && cel->links())
-            transaction.execute(new cmd::UnlinkCel(cel));
+            tx(new cmd::UnlinkCel(cel));
         }
       }
     }
@@ -74,13 +74,13 @@ void UnlinkCelCommand::onExecute(Context* context)
       Cel* cel = writer.cel();
       if (cel && cel->links()) {
         if (cel->layer()->isEditableHierarchy())
-          transaction.execute(new cmd::UnlinkCel(writer.cel()));
+          tx(new cmd::UnlinkCel(writer.cel()));
         else
           nonEditableLayers = true;
       }
     }
 
-    transaction.commit();
+    tx.commit();
   }
 
   if (nonEditableLayers)
diff --git a/src/app/sprite_job.cpp b/src/app/sprite_job.cpp
index f65bbf5f8..6bbc3f67e 100644
--- a/src/app/sprite_job.cpp
+++ b/src/app/sprite_job.cpp
@@ -17,14 +17,14 @@ SpriteJob::SpriteJob(const ContextReader& reader, const char* jobName)
   , m_writer(reader, 500)
   , m_document(m_writer.document())
   , m_sprite(m_writer.sprite())
-  , m_transaction(m_writer.context(), jobName, ModifyDocument)
+  , m_tx(m_writer.context(), jobName, ModifyDocument)
 {
 }
 
 SpriteJob::~SpriteJob()
 {
   if (!isCanceled())
-    m_transaction.commit();
+    m_tx.commit();
 }
 
 void SpriteJob::onJob()
diff --git a/src/app/sprite_job.h b/src/app/sprite_job.h
index 67b7f84f2..d6cbf61b4 100644
--- a/src/app/sprite_job.h
+++ b/src/app/sprite_job.h
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2017  David Capello
+// Copyright (C) 2017-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -11,7 +11,7 @@
 #include "app/context.h"
 #include "app/context_access.h"
 #include "app/job.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "render/task_delegate.h"
 
 #include <functional>
@@ -27,7 +27,7 @@ public:
   ContextWriter& writer() { return m_writer; }
   Doc* document() const { return m_document; }
   Sprite* sprite() const { return m_sprite; }
-  Transaction& transaction() { return m_transaction; }
+  Tx& tx() { return m_tx; }
 
   template<typename T>
   void startJobWithCallback(T&& callback) {
@@ -47,7 +47,7 @@ private:
   ContextWriter m_writer;
   Doc* m_document;
   Sprite* m_sprite;
-  Transaction m_transaction;
+  Tx m_tx;
 
   // Default implementation calls the given function in
   // startJob(). Anyway you can just extended the SpriteJob and
diff --git a/src/app/ui/color_bar.cpp b/src/app/ui/color_bar.cpp
index c937c5da3..6c78037a6 100644
--- a/src/app/ui/color_bar.cpp
+++ b/src/app/ui/color_bar.cpp
@@ -34,7 +34,7 @@
 #include "app/modules/gui.h"
 #include "app/modules/palettes.h"
 #include "app/pref/preferences.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/color_spectrum.h"
 #include "app/ui/color_tint_shade_tone.h"
 #include "app/ui/color_wheel.h"
@@ -541,7 +541,7 @@ void ColorBar::onRemapButtonClick()
     if (sprite) {
       ASSERT(sprite->pixelFormat() == IMAGE_INDEXED);
 
-      Transaction transaction(writer.context(), "Remap Colors", ModifyDocument);
+      Tx tx(writer.context(), "Remap Colors", ModifyDocument);
       bool remapPixels = true;
 
       if (remap.isFor8bit()) {
@@ -553,7 +553,7 @@ void ColorBar::onRemapButtonClick()
         }
 
         if (remap.isInvertible(usedEntries)) {
-          transaction.execute(new cmd::RemapColors(sprite, remap));
+          tx(new cmd::RemapColors(sprite, remap));
           remapPixels = false;
         }
       }
@@ -565,17 +565,17 @@ void ColorBar::onRemapButtonClick()
           ImageRef newImage(Image::createCopy(celImage.get()));
           doc::remap_image(newImage.get(), remap);
 
-          transaction.execute(new cmd::ReplaceImage(
-                                sprite, celImage, newImage));
+          tx(new cmd::ReplaceImage(
+               sprite, celImage, newImage));
         }
       }
 
       color_t oldTransparent = sprite->transparentColor();
       color_t newTransparent = remap[oldTransparent];
       if (oldTransparent != newTransparent)
-        transaction.execute(new cmd::SetTransparentColor(sprite, newTransparent));
+        tx(new cmd::SetTransparentColor(sprite, newTransparent));
 
-      transaction.commit();
+      tx.commit();
     }
     update_screen_for_document(writer.document());
     hideRemap();
@@ -625,9 +625,9 @@ void ColorBar::setPalette(const doc::Palette* newPalette, const std::string& act
     frame_t frame = writer.frame();
     if (sprite &&
         newPalette->countDiff(sprite->palette(frame), nullptr, nullptr)) {
-      Transaction transaction(writer.context(), actionText, ModifyDocument);
-      transaction.execute(new cmd::SetPalette(sprite, frame, newPalette));
-      transaction.commit();
+      Tx tx(writer.context(), actionText, ModifyDocument);
+      tx(new cmd::SetPalette(sprite, frame, newPalette));
+      tx.commit();
     }
   }
   catch (base::Exception& e) {
@@ -647,10 +647,10 @@ void ColorBar::setTransparentIndex(int index)
         sprite->pixelFormat() == IMAGE_INDEXED &&
         int(sprite->transparentColor()) != index) {
       // TODO merge this code with SpritePropertiesCommand
-      Transaction transaction(writer.context(), "Set Transparent Color");
-      DocApi api = writer.document()->getApi(transaction);
+      Tx tx(writer.context(), "Set Transparent Color");
+      DocApi api = writer.document()->getApi(tx);
       api.setSpriteTransparentColor(sprite, index);
-      transaction.commit();
+      tx.commit();
 
       update_screen_for_document(writer.document());
     }
@@ -1180,9 +1180,9 @@ void ColorBar::updateCurrentSpritePalette(const char* operationName)
           cmd->execute(UIContext::instance());
         }
         else {
-          Transaction transaction(writer.context(), operationName, ModifyDocument);
-          transaction.execute(cmd);
-          transaction.commit();
+          Tx tx(writer.context(), operationName, ModifyDocument);
+          tx(cmd);
+          tx.commit();
         }
       }
     }
diff --git a/src/app/ui/doc_view.cpp b/src/app/ui/doc_view.cpp
index 847b4177a..6c94748d4 100644
--- a/src/app/ui/doc_view.cpp
+++ b/src/app/ui/doc_view.cpp
@@ -24,7 +24,7 @@
 #include "app/modules/editors.h"
 #include "app/modules/palettes.h"
 #include "app/pref/preferences.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/editor/editor_customization_delegate.h"
 #include "app/ui/editor/editor_view.h"
@@ -559,19 +559,19 @@ bool DocView::onClear(Context* ctx)
     return false;
 
   {
-    Transaction transaction(writer.context(), "Clear");
-    transaction.execute(new cmd::ClearMask(writer.cel()));
+    Tx tx(writer.context(), "Clear");
+    tx(new cmd::ClearMask(writer.cel()));
 
     // If the cel wasn't deleted by cmd::ClearMask, we trim it.
     if (writer.cel() &&
         writer.cel()->layer()->isTransparent())
-      transaction.execute(new cmd::TrimCel(writer.cel()));
+      tx(new cmd::TrimCel(writer.cel()));
 
     if (visibleMask &&
         !Preferences::instance().selection.keepSelectionAfterClear())
-      transaction.execute(new cmd::DeselectMask(document));
+      tx(new cmd::DeselectMask(document));
 
-    transaction.commit();
+    tx.commit();
   }
 
   if (visibleMask)
diff --git a/src/app/ui/editor/moving_cel_state.cpp b/src/app/ui/editor/moving_cel_state.cpp
index 977e41679..e7eaf5040 100644
--- a/src/app/ui/editor/moving_cel_state.cpp
+++ b/src/app/ui/editor/moving_cel_state.cpp
@@ -15,7 +15,7 @@
 #include "app/context_access.h"
 #include "app/doc_api.h"
 #include "app/doc_range.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/editor/editor_customization_delegate.h"
 #include "app/ui/main_window.h"
@@ -148,8 +148,8 @@ bool MovingCelState::onMouseUp(Editor* editor, MouseMessage* msg)
   if (modified) {
     {
       ContextWriter writer(m_reader, 1000);
-      Transaction transaction(writer.context(), "Cel Movement", ModifyDocument);
-      DocApi api = document->getApi(transaction);
+      Tx tx(writer.context(), "Cel Movement", ModifyDocument);
+      DocApi api = document->getApi(tx);
       gfx::Point intOffset = intCelOffset();
 
       // And now we move the cel (or all selected range) to the new position.
@@ -163,7 +163,7 @@ bool MovingCelState::onMouseUp(Editor* editor, MouseMessage* msg)
             celBounds.w *= m_celScale.w;
             celBounds.h *= m_celScale.h;
           }
-          transaction.execute(new cmd::SetCelBoundsF(cel, celBounds));
+          tx(new cmd::SetCelBoundsF(cel, celBounds));
         }
         else {
           api.setCelPosition(writer.sprite(), cel,
@@ -183,7 +183,7 @@ bool MovingCelState::onMouseUp(Editor* editor, MouseMessage* msg)
                             document->mask()->bounds().y + intOffset.y);
       }
 
-      transaction.commit();
+      tx.commit();
     }
 
     // Redraw all editors. We've to notify all views about this
diff --git a/src/app/ui/editor/moving_selection_state.cpp b/src/app/ui/editor/moving_selection_state.cpp
index 057c127ad..763b73abe 100644
--- a/src/app/ui/editor/moving_selection_state.cpp
+++ b/src/app/ui/editor/moving_selection_state.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2017  David Capello
+// Copyright (C) 2017-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -12,7 +12,7 @@
 
 #include "app/cmd/set_mask_position.h"
 #include "app/context_access.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/skin/skin_theme.h"
 #include "app/ui/status_bar.h"
@@ -55,9 +55,9 @@ EditorState::LeaveAction MovingSelectionState::onLeaveState(Editor* editor, Edit
 
   {
     ContextWriter writer(UIContext::instance(), 1000);
-    Transaction transaction(writer.context(), "Move Selection Edges", DoesntModifyDocument);
-    transaction.execute(new cmd::SetMaskPosition(doc, newOrigin));
-    transaction.commit();
+    Tx tx(writer.context(), "Move Selection Edges", DoesntModifyDocument);
+    tx(new cmd::SetMaskPosition(doc, newOrigin));
+    tx.commit();
   }
 
   doc->resetTransformation();
diff --git a/src/app/ui/editor/moving_slice_state.cpp b/src/app/ui/editor/moving_slice_state.cpp
index 0ba1cdbcb..b654111c7 100644
--- a/src/app/ui/editor/moving_slice_state.cpp
+++ b/src/app/ui/editor/moving_slice_state.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2017  David Capello
+// Copyright (C) 2017-2018  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -12,7 +12,7 @@
 
 #include "app/cmd/set_slice_key.h"
 #include "app/context_access.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/status_bar.h"
 #include "app/ui_context.h"
@@ -43,15 +43,15 @@ bool MovingSliceState::onMouseUp(Editor* editor, MouseMessage* msg)
 {
   {
     ContextWriter writer(UIContext::instance(), 1000);
-    Transaction transaction(writer.context(), "Slice Movement", ModifyDocument);
+    Tx tx(writer.context(), "Slice Movement", ModifyDocument);
 
     doc::SliceKey newKey = m_key;
     m_hit.slice()->insert(editor->frame(), m_keyStart);
 
-    transaction.execute(new cmd::SetSliceKey(m_hit.slice(),
-                                             editor->frame(),
-                                             newKey));
-    transaction.commit();
+    tx(new cmd::SetSliceKey(m_hit.slice(),
+                            editor->frame(),
+                            newKey));
+    tx.commit();
   }
 
   editor->backToPreviousState();
diff --git a/src/app/util/clipboard.cpp b/src/app/util/clipboard.cpp
index d358e7b05..fbeed2fe7 100644
--- a/src/app/util/clipboard.cpp
+++ b/src/app/util/clipboard.cpp
@@ -22,7 +22,7 @@
 #include "app/modules/gfx.h"
 #include "app/modules/gui.h"
 #include "app/pref/preferences.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui/color_bar.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/skin/skin_theme.h"
@@ -251,16 +251,16 @@ void cut(ContextWriter& writer)
   }
   else {
     {
-      Transaction transaction(writer.context(), "Cut");
-      transaction.execute(new cmd::ClearMask(writer.cel()));
+      Tx tx(writer.context(), "Cut");
+      tx(new cmd::ClearMask(writer.cel()));
 
       ASSERT(writer.cel());
       if (writer.cel() &&
           writer.cel()->layer()->isTransparent())
-        transaction.execute(new cmd::TrimCel(writer.cel()));
+        tx(new cmd::TrimCel(writer.cel()));
 
-      transaction.execute(new cmd::DeselectMask(writer.document()));
-      transaction.commit();
+      tx(new cmd::DeselectMask(writer.document()));
+      tx.commit();
     }
     writer.document()->generateMaskBoundaries();
     update_screen_for_document(writer.document());
@@ -406,8 +406,8 @@ void paste()
             return;
           }
 
-          Transaction transaction(UIContext::instance(), "Paste Cels");
-          DocApi api = dstDoc->getApi(transaction);
+          Tx tx(UIContext::instance(), "Paste Cels");
+          DocApi api = dstDoc->getApi(tx);
 
           // Add extra frames if needed
           while (dstFrameFirst+srcRange.frames() > dstSpr->totalFrames())
@@ -480,7 +480,7 @@ void paste()
             }
           }
 
-          transaction.commit();
+          tx.commit();
           editor->invalidate();
           break;
         }
@@ -498,8 +498,8 @@ void paste()
             break;
           }
 
-          Transaction transaction(UIContext::instance(), "Paste Frames");
-          DocApi api = dstDoc->getApi(transaction);
+          Tx tx(UIContext::instance(), "Paste Frames");
+          DocApi api = dstDoc->getApi(tx);
 
           auto srcLayers = srcSpr->allBrowsableLayers();
           auto dstLayers = dstSpr->allBrowsableLayers();
@@ -532,7 +532,7 @@ void paste()
             ++dstFrame;
           }
 
-          transaction.commit();
+          tx.commit();
           editor->invalidate();
           break;
         }
@@ -541,8 +541,8 @@ void paste()
           if (srcDoc->colorMode() != dstDoc->colorMode())
             throw std::runtime_error("You cannot copy layers of document with different color modes");
 
-          Transaction transaction(UIContext::instance(), "Paste Layers");
-          DocApi api = dstDoc->getApi(transaction);
+          Tx tx(UIContext::instance(), "Paste Layers");
+          DocApi api = dstDoc->getApi(tx);
 
           // Remove children if their parent is selected so we only
           // copy the parent.
@@ -583,7 +583,7 @@ void paste()
             srcDoc->copyLayerContent(srcLayer, dstDoc, newLayer);
           }
 
-          transaction.commit();
+          tx.commit();
           editor->invalidate();
           break;
         }
diff --git a/src/app/util/layer_boundaries.cpp b/src/app/util/layer_boundaries.cpp
index 8863fe0d6..1334c50e4 100644
--- a/src/app/util/layer_boundaries.cpp
+++ b/src/app/util/layer_boundaries.cpp
@@ -14,7 +14,7 @@
 #include "app/console.h"
 #include "app/context_access.h"
 #include "app/modules/gui.h"
-#include "app/transaction.h"
+#include "app/tx.h"
 #include "app/ui_context.h"
 #include "doc/cel.h"
 #include "doc/document.h"
@@ -120,9 +120,9 @@ void select_layer_boundaries(Layer* layer,
       }
     }
 
-    Transaction transaction(writer.context(), "Select Layer Boundaries", DoesntModifyDocument);
-    transaction.execute(new cmd::SetMask(doc, &newMask));
-    transaction.commit();
+    Tx tx(writer.context(), "Select Layer Boundaries", DoesntModifyDocument);
+    tx(new cmd::SetMask(doc, &newMask));
+    tx.commit();
 
     doc->resetTransformation();
     doc->generateMaskBoundaries();