Use ModifierKeys instead of Keyboard.IsKeyDown.

src/Libraries/AvalonDock/AvalonDock/DockingManager.cs

@@ -1054,7 +1054,8 @@ namespace AvalonDock
         
         protected override void OnKeyDown(KeyEventArgs e)
         {
-            bool isCtrlDown = Keyboard.IsKeyDown(Key.LeftCtrl) || Keyboard.IsKeyDown(Key.RightCtrl);
+            // accept Control or Control+Shift
+            bool isCtrlDown = (Keyboard.Modifiers & ~ModifierKeys.Shift) == ModifierKeys.Control;
             bool _navigatorWindowIsVisible = navigatorWindow != null ? navigatorWindow.IsVisible : false;
             Debug.WriteLine(string.Format("OnKeyDn {0} CtrlDn={1}", e.Key, isCtrlDown));
 
@@ -1078,7 +1079,8 @@ namespace AvalonDock
 
         protected override void OnKeyUp(KeyEventArgs e)
         {
-        	 bool isCtrlDown = Keyboard.IsKeyDown(Key.LeftCtrl) || Keyboard.IsKeyDown(Key.RightCtrl);
+            // accept Control or Control+Shift
+            bool isCtrlDown = (Keyboard.Modifiers & ~ModifierKeys.Shift) == ModifierKeys.Control;
             bool _navigatorWindowIsVisible = navigatorWindow != null ? navigatorWindow.IsVisible : false;
             Debug.WriteLine(string.Format("OnKeyUp {0} CtrlDn={1}", e.Key, isCtrlDown));
 
@@ -1091,7 +1093,7 @@ namespace AvalonDock
                 }
 
                 if (_navigatorWindowIsVisible)
-                    navigatorWindow.HandleKey(e.Key); 
+                    e.Handled = navigatorWindow.HandleKey(e.Key); 
             }
             else
             {

src/Libraries/AvalonDock/AvalonDock/NavigatorWindow.cs

@@ -196,10 +196,10 @@ namespace AvalonDock
         {
             if (key == Key.Tab)
             {
-            	if (Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift))
-            		 MoveToPreviousContent();
-            	 else
-               	 MoveToNextContent();
+                if ((Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift)
+                    MoveToPreviousContent();
+                else
+                    MoveToNextContent();
                 return true;
             }
             else if (key == Key.Down)

src/Main/Base/Project/Src/Gui/AbstractViewContent.cs

@@ -415,7 +415,7 @@ namespace ICSharpCode.SharpDevelop.Gui
 				else if (files.Count > 0)
 					return files[0].FileName;
 				else
-					return "[Default Info Tip]";
+					return null;
 			}
 		}