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Tooltips are override_redirect windows, which means that the window manager doesn't touch them at all and the application is _completely_ responsible for that kind of window, which includes showing, hiding, moving and resizing as well as focus.
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override_redirect windows (not only tooltips, but also menus etc.) are completely managed by the application; it's neither the WM's job to deal with them nor is the WM allowed to do so.
From the first comments in the bug filed upstream in compiz it seems that they think the window manager is not responsible for the behaviour of tooltips (http:// bugs.opencompos iting.org/ show_bug. cgi?id= 1232#c1):
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Tooltips are override_redirect windows, which means that the window manager doesn't touch them at all and the application is _completely_ responsible for that kind of window, which includes showing, hiding, moving and resizing as well as focus.
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override_redirect windows (not only tooltips, but also menus etc.) are completely managed by the application; it's neither the WM's job to deal with them nor is the WM allowed to do so.