QWinTaskbarProgress (QtWinExtras) on Vista: is it supported?

  • Hello,

    I use a QWinTaskbarProgress (Qt 5.2.0 new feature) on Windows 7. It works correctly.

    This is integrated in an open source project named "QtlMovie":http://qtlmovie.sourceforge.net/. One user "reported":http://forum.videohelp.com/threads/359441-Announcing-QtlMovie-a-specialized-graphical-front-end-to-FFmpeg that the application crashes on exit on Windows Vista. I do not have any Vista system here to reproduce or analyze the problem. I provided a specific version of the application to this user without the QWinTaskbarProgress and everything else unchanged in the application. He reported that the crash no longer occured.

    Is there any experience of QWinTaskbarProgress working / not working on Vista ?

    Note the application is statically linked using a static version of Qt as described "here":http://qt-project.org/forums/viewthread/35655/.

    Here are a few code snippets describing all references to the QWinTaskbarProgress. Is there anything incorrect here? Remember that this works correctly on Windows 7 (64 bits).

    @ QWinTaskbarButton* _taskbarButton; //!< The application button in the Windows task bar.
    QWinTaskbarProgress* _taskbarProgress; //!< The progress indicator in the Windows task bar.@

    @ // The following sequence is a mystery. If not present, the taskbar progress does not work.
    // But the Qt documentation is not really clear on what this does.
    if (QtWin::isCompositionEnabled()) {
    else {

        // Setup the Windows taskbar button.
        _taskbarButton = new QWinTaskbarButton(this);
        _taskbarProgress = _taskbarButton->progress();
        _taskbarProgress->setRange(0, 1000);@

    When the lengthy operation starts/stops:
    @ _taskbarProgress->setVisible(started);@

    @ _taskbarProgress->setValue(progressValue); // in the range 0 to 1000@

    Nothing else.

    Without further information, I currently disable the usage of the QWinTaskbarButton on versions of Windows prior to Win 7.

    Thanks for your feedback.

Log in to reply