Hi, Don't know enough about splitters to really help, but I think chasing the route of 'recalling OnCreateClient' is the wrong way to go. I think MFC calls this to divide the available client area of a frame window up before creation (then it knows how to create the relevant views). I made a class that could replace views, and it could split an existing view, so I would have thought it was possible to do the opposite. I am probably wrong, but maybe try: 1. splitting the main window into 1 (sound stupid, but then you have a splitter created and attached to the frame window) 2. divide the main splitter pane up when splitting 3. replace the main splitter pane with just the single view when unsplitting. This would be how I would approach the problem, though I admit it seems completely unelegant. Sorry I couldn't be of more help, Simon