fix performance issue when activating MainWindow

src/Main/Base/Project/Src/Editor/IDocumentBaseVersionProvider.cs

@@ -65,9 +65,11 @@ namespace ICSharpCode.SharpDevelop.Editor
 
 		void MainWindowActivated(object sender, EventArgs e)
 		{
+			if (alreadyCalled) {
 				alreadyCalled = false;
 				actions();
 			}
+		}
 		
 		bool alreadyCalled;