Maximizing and closing Documentwindow maximizes all windows

I've encountered a strange bug in my program, and I'm not sure if its something wrong on my end or something I don't know about actipro.

I have a standard MDI host with some windows in it. Whenever I maximize a document window and then close it before un-maximizing it, all other document windows in that mdi host are now maximized. If I maximize the window, and then un-maximize it, everything is fine.

Any ideas what's going on here?

Thanks,
Stephen