100% reproducible for me, in both the Files and Projects tool windows (but doesn't repro in Defs, for example).
I would swear I reported this a couple years ago during the Qt conversion.
Anyway, it's an easy repro:
1. Move mouse to bottom pixel of an entry in the list.
2. Double click. (Be careful not to jostle the mouse, of course).
Expected: takes action on the highlighted entry.
Actual: momentarily highlights the entry below it, and takes action on the (incorrect) newly highlighted entry, then highlighted the original entry again.