When docking a window, it is sometimes doubled

[Cyp]

To reproduce, open/close windows, dock/undock them and switch between windows randomly, until it happens. Can't find a pattern in when/why it happens.

Also, if selecting the main scribus window, then selecting a popup window, the popup window flickers (disappearing once then reappearing) quickly.

Using KDE.

[aoloe]

I've submitted it as https://bugs.scribus.net/view.php?id=15698

As I wrote there, hard to say if the Scribus side can do much (or it's even a Scribus issue...). But it's IMO good to have this issue tracked.