Joel Spolsky has an old post on this. Apparently, clicking in a window on the Mac brings that _process_ into the foreground, but not necessarily that window. If

Joel Spolsky has an old post on this. Apparently, clicking in a window on the Mac brings that _process_ into the foreground, but not necessarily that window. If process A is in the foreground with window 1, and process B has windows 2 and 3 with 2 in front of 3, so the current window stacking order is 1,2,3 then the effect of clicking in window 3 is in fact to bring window 2 forwards, so the window stacking order is now 2,3,1. Widgets, toolbars and other floating things that are separate windows as far as the window manager is concerned can also affect this. For example, GIMP or other programs that have palettes need to enforce that "the palette is always in front of the main window", which I imagine is handled differently on the Mac to other OSes.