Comment 13 for bug 1131385

in
unity-shared/PluginAdapter.cpp

 621 if (window->defaultViewport() == screen_vp &&
 622 window->isViewable() && window->isMapped() &&
 623 !window->minimized() && !window->inShowDesktopMode() &&
 624 !(window->state() & CompWindowStateAboveMask) &&
 625 !(window->type() & CompWindowTypeSplashMask) &&
 626 !(window->type() & CompWindowTypeDockMask) &&
 627 !window->overrideRedirect() &&
 628 std::find(our_xids.begin(), our_xids.end(), window->id()) == our_xids.end())
 629 {
 630 return window->id();
 631 }

only the return value of window->state() is changed from the 'normal status' (8192) to 'always on top status' (8704)

So now the question is, why !(window->state() & CompWindowStateAboveMask) is false?