Fixed ProjectBrowserPad selecting the currently opened file.

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/trunk@5537 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/Main/Base/Project/Src/Gui/Pads/ProjectBrowser/ProjectBrowserPad.cs

@@ -145,25 +145,36 @@ namespace ICSharpCode.SharpDevelop.Project
 			projectBrowserPanel.Clear();
 		}
 		
-		string lastFileName;
+		bool activeContentChangedEnqueued;
 		
 		void ActiveContentChanged(object sender, EventArgs e)
 		{
+			// this event may occur several times quickly after another (e.g. when opening or closing multiple files)
+			// do the potentially expensive selection of the item in the tree view only once after the last change
+			if (!activeContentChangedEnqueued) {
+				activeContentChangedEnqueued = true;
+				WorkbenchSingleton.SafeThreadAsyncCall(ActiveContentChangedInvoked);
+			}
+		}
+		
+		void ActiveContentChangedInvoked()
+		{
+			activeContentChangedEnqueued = false;
 			if (WorkbenchSingleton.Workbench.ActiveContent == this) {
 				projectBrowserPanel.ProjectBrowserControl.PadActivated();
 			} else {
-				IViewContent content = WorkbenchSingleton.Workbench.ActiveViewContent;
+				// we don't use ActiveViewContent here as this is the ActiveContent change event handler
+				IViewContent content = WorkbenchSingleton.Workbench.ActiveContent as IViewContent;
 				if (content == null)
 					return;
 				string fileName = content.PrimaryFileName;
-				if (fileName == null || lastFileName == fileName) {
+				if (fileName == null) {
 					return;
 				}
 				
 				if (!FileUtility.IsValidPath(fileName)) {
 					return;
 				}
-				lastFileName = fileName;
 				projectBrowserPanel.SelectFile(fileName);
 			}
 		}