Sorry for asking loads of questions recently , I really appreciate the help. I have an issue when I have an NSView that I want to display in different places, what happens is that the second time you view the subview it fails to appear. I have created an example application that shows the problem. If you switch to the second tab view at the top (which also has a subview with the same view in it.) and then switch back to the first tab the subview has disappeared. I'd like it still to appear in the first sub-tabview when switching back, what am I doing wrong so it doesn't appear, is there some documentation I need to read? No errors appear on the console.