private void PushToUndoStack(ToolObjectPair action, bool clearRedoStack)
 {
     undoStack.Push(action);
       if (clearRedoStack)
     redoStack.Clear();
       OnPropertyChanged("RedoAvailable");
 }
 private void PushToRedoStack(ToolObjectPair action)
 {
     redoStack.Push(action);
       OnPropertyChanged("RedoAvailable");
 }