[REG Qt4->Qt5] XCB: Qt::(X11)BypassWindowManagerHint doesn't work properly

From docs:

Bypass the window manager completely. This results in a borderless window that is not managed at all (i.e., no keyboard input unless you call QWidget::activateWindow() manually).

This works properly on Qt4 - the window can be focused only by QWidget::activateWindow().

On Qt5 the window with Qt::BypassWindowManagerHint can be focused by mouse click (incorrect). This causes problems on X11 tray icons (not DBus) - tray icon can take focus, so the previously focused window is now unfocused (after clicking on tray icon).
The problem is also on tooltips - when you click on tooltip, then it takes a focus before disappear, so it causes that Qt "thinks" that the original window doesn't have a focus (e.g. text cursor stops blinking). You must click on the original window to get it work properly.