diff --git a/src/app/ui/color_bar.cpp b/src/app/ui/color_bar.cpp
index 0665b4c69..e5bf1acd7 100644
--- a/src/app/ui/color_bar.cpp
+++ b/src/app/ui/color_bar.cpp
@@ -21,6 +21,7 @@
 #include "app/commands/params.h"
 #include "app/console.h"
 #include "app/context_access.h"
+#include "app/document_api.h"
 #include "app/ini_file.h"
 #include "app/modules/gui.h"
 #include "app/modules/palettes.h"
@@ -376,8 +377,10 @@ void ColorBar::onPaletteViewIndexChange(int index, ui::MouseButtons buttons)
 
   if ((buttons & kButtonRight) == kButtonRight)
     setBgColor(color);
-  else
+  else if ((buttons & kButtonLeft) == kButtonLeft)
     setFgColor(color);
+  else if ((buttons & kButtonMiddle) == kButtonMiddle)
+    setTransparentIndex(index);
 
   m_lock = false;
 }
@@ -421,6 +424,29 @@ void ColorBar::setPalette(const doc::Palette* newPalette, const std::string& act
   getManager()->invalidate();
 }
 
+void ColorBar::setTransparentIndex(int index)
+{
+  try {
+    ContextWriter writer(UIContext::instance(), 500);
+    Sprite* sprite = writer.sprite();
+    frame_t frame = writer.frame();
+    if (sprite &&
+        sprite->pixelFormat() == IMAGE_INDEXED &&
+        sprite->transparentColor() != index) {
+      // TODO merge this code with SpritePropertiesCommand
+      Transaction transaction(writer.context(), "Set Transparent Color");
+      DocumentApi api = writer.document()->getApi(transaction);
+      api.setSpriteTransparentColor(sprite, index);
+      transaction.commit();
+
+      update_screen_for_document(writer.document());
+    }
+  }
+  catch (base::Exception& e) {
+    Console::showException(e);
+  }
+}
+
 void ColorBar::onPaletteViewChangeSize(int boxsize)
 {
   Preferences::instance().colorBar.boxSize(boxsize);
diff --git a/src/app/ui/color_bar.h b/src/app/ui/color_bar.h
index f2ce7cffa..c807cb525 100644
--- a/src/app/ui/color_bar.h
+++ b/src/app/ui/color_bar.h
@@ -99,6 +99,7 @@ namespace app {
     void destroyRemap();
     void applyRemap(const doc::Remap& remap, const doc::Palette* newPalette, const std::string& actionText);
     void setPalette(const doc::Palette* newPalette, const std::string& actionText);
+    void setTransparentIndex(int index);
 
     class ScrollableView : public ui::View {
     public:
diff --git a/src/app/ui/palette_view.cpp b/src/app/ui/palette_view.cpp
index 160fed591..0b3ab5786 100644
--- a/src/app/ui/palette_view.cpp
+++ b/src/app/ui/palette_view.cpp
@@ -318,19 +318,23 @@ bool PaletteView::onProcessMessage(Message* msg)
             app::Color::fromIndex(idx), 255);
 
           if (hasCapture() && (idx != m_currentEntry || msg->type() == kMouseDownMessage)) {
-            if (!msg->ctrlPressed())
-              deselect();
+            MouseButtons buttons = mouseMsg->buttons();
 
-            if (msg->type() == kMouseMoveMessage)
-              selectRange(m_rangeAnchor, idx);
-            else {
-              selectColor(idx);
-              m_selectedEntries[idx] = true;
+            if ((buttons & kButtonMiddle) == 0) {
+              if (!msg->ctrlPressed())
+                deselect();
+
+              if (msg->type() == kMouseMoveMessage)
+                selectRange(m_rangeAnchor, idx);
+              else {
+                selectColor(idx);
+                m_selectedEntries[idx] = true;
+              }
             }
 
             // Emit signal
             if (m_delegate)
-              m_delegate->onPaletteViewIndexChange(idx, mouseMsg->buttons());
+              m_delegate->onPaletteViewIndexChange(idx, buttons);
           }
         }
       }