The active window doesn't switch to the foreground; the texture window is always on top preventing proper cascading. Camera and 2D can't be on the sceen at the same time, selecting one moves the other to behind the main window. And all windows don't minimize/maximize along with the main program window but independently.

Another case where layout B is neglected (first one being Netradiant with its presisting bugfeature that renders the ChangeViews command useless). 

It's a known issue, though it seems to be one that affects GTK+, so it's a little out of the hands of the GtkRadiant team, and why it also affects NetRadiant.

I believe it has been reported to the GTK+ developers, but it's up to them to fix it.