Created attachment 49147 [details] Test case Version: SVN (using Devel) OS: Linux I'm not sure whether this is incorrect behaviour on KWin's part or not, but it is annoying (see http://code.google.com/p/cellwriter/issues/detail?id=34). When an application sets the input flag of WM_HINTS to false (preventing the window manager from passing focus to it), pressing a mouse button down on the window when running under KWin sends an XLeaveWindowEvent to the window. On other window managers this doesn't happen (the ButtonPress event gets sent, but not the LeaveWindow/Crossing event). Reproducible: Always Attached is are two test cases, one in GTK+ and one in Qt. Run make to build them, and then run ./gtk-test or ./qt-test to run one or the other. The apps basically just set the input hint to false and print out logs of LeaveWindow events. The GTK+ one also prints out button press events (you can see that the LeaveWindow event happens before the ButtonPress event).
I should point out that the other window managers I've tried are Metacity and whatever XFCE4 uses. I tested all three in an XFCE4 environment, to make sure that it was just the window manager.
*** This bug has been marked as a duplicate of bug 234926 ***