Dragging the tab bar in tabbed windows overrides the style sheet

[PiispaH]

Sometimes when messing around with a specification of an Importer, all of the previously dark menu elements like buttons turn grey. When this happens a small icon usually indicating a drop-down list appears in the corner of the hamburger menu icon. I have seen this happen a few times when doing things like clicking things randomly and selecting other windows. I think this usually happens when selecting a different window.

[PiispaH]

This can happen on any window that can have multiple tabs. When the window is dragged around from the bar where the tabs appear, the styling of the UI elements seems to go back to the defaults instead of using the style-sheet provided in config.py in Toolbox.

[jkiviluo]

I wonder if this is QT problem rather than ours and if so, it might get fixed by QT.