QDialog not reappearing after hiding parent window on Ubuntu

  • I have a program that hides in a system tray area. It uses few dialogs for interactions with user. The problem is when i hide my app to tray with some dialogs still open. After restoring the windows to normal stated, dialogs disappear. The problem occurs on Ubuntu 17.10 with Qt 5.9.2, but I suppose that other Linux distributions may have this problem as well. I tested it with Plasma, GNOME and Unity. Same result. Windows version of my program works correctly, windows are hidden and restored as expected. Simple code can present the issue:

    #include <QtWidgets>
    #include <QtGui>
    int main(int argc, char *argv[]) {
        QApplication a(argc, argv);
        QWidget w;
        QDialog d(&w);
        QTimer::singleShot(1000, [&] { w.show(); });
        QTimer::singleShot(2000, [&] { d.show(); });
        QTimer::singleShot(3000, [&] { w.showMinimized(); });
        QTimer::singleShot(4000, [&] { w.hide(); });
        QTimer::singleShot(5000, [&] { w.show(); });
        QTimer::singleShot(6000, [&] { w.showNormal(); });

    After w.hide() dialog won't show again. Any additional calls of dialog methods like show(), showNormal() do nothing. Any ideas? Is this a bug, or is there something wrong with my code?

  • Lifetime Qt Champion

    Hi and welcome to devnet,

    What do you mean by disappear ?
    Do they get hidden by the other window or just invisible ?

  • Invisible. I can't manage to get the dialog shown with parent window.
    Before: QWidget and QDialog on top of it.
    After: QWidget only. QDialog disappeared.

  • Lifetime Qt Champion

    Are you using your distribution provided Qt ?

  • I use Qt installed with MaintenanceTool. I asked this question on other forum and one person has confirmed having same issue on Ubuntu 18.04, so I think that this problem is not only related to my configuration.

  • Moderators

    @artudi54 Is the QDialog modal using QDialog::exec() or is it shown with QDialog::show()?

    Edit: nevermind I see the code above, lol.. I'll test for you on my linux real quick.

  • Moderators

    @artudi54 Tested with gnome on arch and it does the same thing. I'd say this is a bug since d.show() never pulls the window back up.

    I would file the bug with Qt.

    To work around it I just made sure to call d.hide() before hiding the main window. Then after w.show() just call d.show() again.

Log in to reply

Looks like your connection to Qt Forum was lost, please wait while we try to reconnect.