Important: Please read the Qt Code of Conduct -

Mac OS X Translucent window performance problems and glitches.

  • Hi all,

    I've developed a Qt/QML application which I display with a translucent QDeclarativeView in a translucent frameless QMainWindow (see this). The application is fairly complex with a a few ListViews inside and some threads that poll a remote server for data and feed the views. The program runs flawlessly and at full speed without glitches on Windows 7. But when I compile and run it on Snow Leopard I've got the following problems;

    GUI rendering is slow in general
    When I scroll the ListView with the mouse wheel, the wheel actions affect the underlying window and my GUI flickers as if it can't render fast enough. Also often when I click something on my GUI, the mouse click just passes through my window onto the underlying window and brings it in front.
    Mouse actions feel awkward. There is a significant delay.
    These problems are present on both the Release and Debug builds with/without gdb attached.

    The problems sound related to me but I'm confused. Why would an application running perfectly on Win7 perform badly on Snow Leopard ? Am I missing some specific configuration ? Any help is appreciated.

  • I have filed a bug report and attached videos to it. I would be grateful if somebody could check it.


  • When a Qt window with Qt::FramelessWindowHint and Qt::WA_TranslucentBackground properties is on top of another application window which updates its window (e.g. A video player, a terminal screen showing a constant flow of output ('find . ') ) . The window flickers and the contents of the other application window bleeds onto it. Also the mouse events are caught by the underlying as if the Qt window doesn't paint itself.

    Can anyone check this bug report ? There I attached a minimal sample and 3 videos displaying the behaviour.

  • Merged by me, because it seems to deal with the very same issue.

Log in to reply