diff --git a/data/skins/default/sheet.png b/data/skins/default/sheet.png
index bc0ab7ac1..603278200 100644
Binary files a/data/skins/default/sheet.png and b/data/skins/default/sheet.png differ
diff --git a/data/skins/default/skin.xml b/data/skins/default/skin.xml
index ce0f74400..dfd22cd04 100644
--- a/data/skins/default/skin.xml
+++ b/data/skins/default/skin.xml
@@ -329,6 +329,10 @@
     <part id="timeline_continuous_active"       x="288" y="36" w="12" h="12" />
     <part id="timeline_discontinuous_normal"    x="276" y="48" w="12" h="12" />
     <part id="timeline_discontinuous_active"    x="288" y="48" w="12" h="12" />
+    <part id="timeline_closed_group_normal"     x="276" y="60" w="12" h="12" />
+    <part id="timeline_closed_group_active"     x="288" y="60" w="12" h="12" />
+    <part id="timeline_open_group_normal"       x="276" y="72" w="12" h="12" />
+    <part id="timeline_open_group_active"       x="288" y="72" w="12" h="12" />
     <part id="timeline_empty_frame_normal"      x="240" y="60" w="12" h="12" />
     <part id="timeline_empty_frame_active"      x="252" y="60" w="12" h="12" />
     <part id="timeline_keyframe_normal"         x="240" y="72" w="12" h="12" />
@@ -560,6 +564,20 @@
       <icon part="timeline_discontinuous_active" />
     </style>
 
+    <!-- timeline_group -->
+    <style id="timeline_closed_group" base="timeline_box">
+      <icon part="timeline_closed_group_normal" align="center" valign="middle" />
+    </style>
+    <style id="timeline_closed_group:active">
+      <icon part="timeline_closed_group_active" />
+    </style>
+    <style id="timeline_open_group" base="timeline_box">
+      <icon part="timeline_open_group_normal" align="center" valign="middle" />
+    </style>
+    <style id="timeline_open_group:active">
+      <icon part="timeline_open_group_active" />
+    </style>
+
     <!-- timeline_layer -->
     <style id="timeline_layer" base="timeline_box">
       <text align="left" valign="middle" padding-left="4" />
diff --git a/src/app/ui/timeline.cpp b/src/app/ui/timeline.cpp
index e8bcc972e..17b3f187c 100644
--- a/src/app/ui/timeline.cpp
+++ b/src/app/ui/timeline.cpp
@@ -662,8 +662,13 @@ bool Timeline::onProcessMessage(Message* msg)
           case PART_LAYER_CONTINUOUS_ICON:
             if (m_hot.layer == m_clk.layer && validLayer(m_hot.layer)) {
               Layer* layer = m_layers[m_clk.layer];
-              ASSERT(layer != NULL);
-              layer->setContinuous(!layer->isContinuous());
+              ASSERT(layer);
+              if (layer) {
+                if (layer->isImage())
+                  layer->setContinuous(!layer->isContinuous());
+                else if (layer->isGroup())
+                  layer->setCollapsed(!layer->isCollapsed());
+              }
             }
             break;
 
@@ -1355,13 +1360,22 @@ void Timeline::drawLayer(ui::Graphics* g, LayerIndex layerIdx)
     (hotlayer && m_hot.part == PART_LAYER_PADLOCK_ICON),
     (clklayer && m_clk.part == PART_LAYER_PADLOCK_ICON));
 
-  // Draw the continuous flag.
+  // Draw the continuous flag/group icon.
   bounds = getPartBounds(Hit(PART_LAYER_CONTINUOUS_ICON, layerIdx));
-  drawPart(g, bounds, NULL,
-    layer->isContinuous() ? styles.timelineContinuous(): styles.timelineDiscontinuous(),
-    is_active,
-    (hotlayer && m_hot.part == PART_LAYER_CONTINUOUS_ICON),
-    (clklayer && m_clk.part == PART_LAYER_CONTINUOUS_ICON));
+  if (layer->isImage()) {
+    drawPart(g, bounds, NULL,
+             layer->isContinuous() ? styles.timelineContinuous(): styles.timelineDiscontinuous(),
+             is_active,
+             (hotlayer && m_hot.part == PART_LAYER_CONTINUOUS_ICON),
+             (clklayer && m_clk.part == PART_LAYER_CONTINUOUS_ICON));
+  }
+  else if (layer->isGroup()) {
+    drawPart(g, bounds, NULL,
+             layer->isCollapsed() ? styles.timelineClosedGroup(): styles.timelineOpenGroup(),
+             is_active,
+             (hotlayer && m_hot.part == PART_LAYER_CONTINUOUS_ICON),
+             (clklayer && m_clk.part == PART_LAYER_CONTINUOUS_ICON));
+  }
 
   // Get the layer's name bounds.
   bounds = getPartBounds(Hit(PART_LAYER_TEXT, layerIdx));
@@ -2179,11 +2193,14 @@ void Timeline::updateStatusBar(ui::Message* msg)
         break;
 
       case PART_LAYER_CONTINUOUS_ICON:
-        if (layer != NULL) {
-          sb->setStatusText(0, "Layer '%s' is %s (%s)",
-            layer->name().c_str(),
-            layer->isContinuous() ? "continuous": "discontinuous",
-            layer->isContinuous() ? "prefer linked cels/frames": "prefer individual cels/frames");
+        if (layer) {
+          if (layer->isImage())
+            sb->setStatusText(0, "Layer '%s' is %s (%s)",
+                              layer->name().c_str(),
+                              layer->isContinuous() ? "continuous": "discontinuous",
+                              layer->isContinuous() ? "prefer linked cels/frames": "prefer individual cels/frames");
+          else if (layer->isGroup())
+            sb->setStatusText(0, "Group '%s'", layer->name().c_str());
           return;
         }
         break;
diff --git a/src/doc/layer.h b/src/doc/layer.h
index bf7c83adc..36c9564f3 100644
--- a/src/doc/layer.h
+++ b/src/doc/layer.h
@@ -35,6 +35,7 @@ namespace doc {
     LockMove   = 4,             // Cannot be moved
     Background = 8,             // Stack order cannot be changed
     Continuous = 16,            // Prefer to link cels when the user copy them
+    Collapsed  = 32,            // Prefer to show this group layer collapsed
 
     BackgroundLayerFlags = LockMove | Background,
   };
@@ -62,17 +63,21 @@ namespace doc {
     bool isImage() const { return type() == ObjectType::LayerImage; }
     bool isGroup() const { return type() == ObjectType::LayerGroup; }
 
-    bool isBackground() const { return hasFlags(LayerFlags::Background); }
-    bool isVisible() const    { return hasFlags(LayerFlags::Visible); }
-    bool isEditable() const   { return hasFlags(LayerFlags::Editable); }
-    bool isMovable() const    { return !hasFlags(LayerFlags::LockMove); }
-    bool isContinuous() const { return hasFlags(LayerFlags::Continuous); }
+    bool isBackground() const  { return hasFlags(LayerFlags::Background); }
+    bool isTransparent() const { return !hasFlags(LayerFlags::Background); }
+    bool isVisible() const     { return hasFlags(LayerFlags::Visible); }
+    bool isEditable() const    { return hasFlags(LayerFlags::Editable); }
+    bool isMovable() const     { return !hasFlags(LayerFlags::LockMove); }
+    bool isContinuous() const  { return hasFlags(LayerFlags::Continuous); }
+    bool isCollapsed() const   { return hasFlags(LayerFlags::Collapsed); }
+    bool isExpanded() const    { return !hasFlags(LayerFlags::Collapsed); }
 
     void setBackground(bool state) { switchFlags(LayerFlags::Background, state); }
     void setVisible   (bool state) { switchFlags(LayerFlags::Visible, state); }
     void setEditable  (bool state) { switchFlags(LayerFlags::Editable, state); }
     void setMovable   (bool state) { switchFlags(LayerFlags::LockMove, !state); }
     void setContinuous(bool state) { switchFlags(LayerFlags::Continuous, state); }
+    void setCollapsed (bool state) { switchFlags(LayerFlags::Collapsed, state); }
 
     LayerFlags flags() const {
       return m_flags;