[DiapDealer]

OK. The "one pixel" thing is not really accurate for me, but I can confirm that the ToC widget (when configured on top left above Book Browser) does continuously shrink when closing/reopening Sigil when Sigil IS MAXIMIZED. I don't often run programs maximized these days, so I didn't notice at first. It seems to only shrink so far and then stop (in my testing). But it's definitely not remembering its geometry when maximized and closing/opening sigil. The theme has no effect on this issue.

P.S. It could be Book Browser growing for all I know!