diff --git a/src/Main/Base/Project/Src/Gui/Components/ExtTreeView/ExtTreeNode.cs b/src/Main/Base/Project/Src/Gui/Components/ExtTreeView/ExtTreeNode.cs
index f9653635f8..be0573509d 100644
--- a/src/Main/Base/Project/Src/Gui/Components/ExtTreeView/ExtTreeNode.cs
+++ b/src/Main/Base/Project/Src/Gui/Components/ExtTreeView/ExtTreeNode.cs
@@ -99,6 +99,7 @@ namespace ICSharpCode.SharpDevelop.Gui
 		
 		public virtual void ActivateItem()
 		{
+			this.Toggle();
 		}
 		
 		public virtual void CheckedChanged()
diff --git a/src/Main/Base/Project/Src/Gui/Components/ExtTreeView/ExtTreeView.cs b/src/Main/Base/Project/Src/Gui/Components/ExtTreeView/ExtTreeView.cs
index 2e9d4ea9cc..b2f3a34833 100644
--- a/src/Main/Base/Project/Src/Gui/Components/ExtTreeView/ExtTreeView.cs
+++ b/src/Main/Base/Project/Src/Gui/Components/ExtTreeView/ExtTreeView.cs
@@ -181,9 +181,15 @@ namespace ICSharpCode.SharpDevelop.Gui
 		bool inRefresh;
 		protected override void OnBeforeExpand(TreeViewCancelEventArgs e)
 		{
+			if (mouseClickNum == 2) {
+				mouseClickNum = 0; // only intercept first occurrance, don't prevent expansion by ActivateItem on double click
+				e.Cancel = true;
+				return;
+			}
 			base.OnBeforeExpand(e);
-			if (e.Node == null)
+			if (e.Node == null) {
 				return;
+			}
 			try {
 				if (e.Node is ExtTreeNode) {
 					if (((ExtTreeNode)e.Node).IsInitialized == false) {
@@ -219,9 +225,13 @@ namespace ICSharpCode.SharpDevelop.Gui
 			}
 		}
 		
-		
 		protected override void OnBeforeCollapse(TreeViewCancelEventArgs e)
 		{
+			if (mouseClickNum == 2) {
+				mouseClickNum = 0; // only intercept first occurrance, don't prevent collapsing by ActivateItem on double click
+				e.Cancel = true;
+				return;
+			}
 			base.OnBeforeCollapse(e);
 			if (e.Node is ExtTreeNode) {
 				((ExtTreeNode)e.Node).Collapsing();
@@ -263,8 +273,11 @@ namespace ICSharpCode.SharpDevelop.Gui
 			}
 		}
 		
+		int mouseClickNum; // 0 if mouse button is not pressed, otherwise click number (1=normal, 2=double click)
+		
 		protected override void OnMouseDown(MouseEventArgs e)
 		{
+			mouseClickNum = e.Clicks;
 			base.OnMouseDown(e);
 			TreeNode node = GetNodeAt(e.X, e.Y);
 			if (node != null) {
@@ -278,6 +291,12 @@ namespace ICSharpCode.SharpDevelop.Gui
 			}
 		}
 		
+		protected override void OnMouseUp(MouseEventArgs e)
+		{
+			mouseClickNum = 0;
+			base.OnMouseUp(e);
+		}
+		
 		protected override void OnBeforeSelect(TreeViewCancelEventArgs e)
 		{
 			// setting the context menu must be done by BeforeSelect because