Use case: 
In a chat application when showing a notification about a new message, the default action is to "Open" the respective view which holds the new message:

    auto *msg = KNotification::event(...);
    msg->setDefaultAction(i18n("Open"));
    connect(msg, &KNotification::defaultActivated, window, [] {
        window->show();
        window->raise();
        KWindowSystem::activateWindow(window->winId());
    });

If the window is currently on another virtual desktop, given the intent of the user to open/see the new message when activating the action, one would expect that the window system/shell switches the virtual desktop as needed to show the window.

Instead at least with KWin/Plasma on these calls only the window is highlighted on the taskbar, but the virtual desktop not switched. So the user has to do a further action (e.g. click the highlighted window entry) to finally get to the window.

Assumption: this might be related to focus stealing handling? So there needs to be some way for the notification system to tell the window system that the window activation requested by the application is due to a start/activation like event from the notification. Possibly something with X11 startup id/Wayland activation token?

Seen in Konversation & NeoChat.