I don't use Plasma but I use qt5ct to theme qt/kde applications. An issue I have is that when I double click an opened image to make it fullscreen and then double click to restore, the theme is gone, i.e it goes from the dark theme I configured to a light theme. Restarting Gwenview restores the theme. This is probably out of scope but I'm posting in case it leads to some actual problem.
Thank you for the bug report. Unfortunately we were not able to get to it yet. Can we ask you to please check if this is still an issue with Gwenview 24.12.3?
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