I have a glossary screen where different entries can be viewed, selected from a keyword list. This fills another box with information. I have the scrollbar for the info box set to be "insensitive" when unscrollable, and insensitive_thumb is None.
Depending on certain circumstances, one of two things happens.
- If the box currently has a lot of text, enough to overflow, the scrollbar thumb will change size accordingly when selecting a new entry. If there's less than the fold, it disappears.
- If the box currently has enough text to not overflow, the thumb does not update until a second update happens - re-clicking the same entry, another overflowing entry, or hovering the mouse over the scrollbar.
I've provided a demo script to demonstrate.
(I thought for sure I'd already posted about this in the past, but couldn't find the topic. I at least here determined the cause is something to do with "insensitive" style.)