hide and show palettes (F9) breaks drag and drop
Using the latest nightly Linux AppImage (OS: KDE neon User Edition 5.15, Arch.: x86_64, MuseScore version (64-bit): 18.104.22.16802, revision: 27c146f), if I show and hide the palettes once or twice, drag and drop from the palettes to the score stops working. This bug also happens in MuseScore 3.0.5 and 3.1 BETA, but does not happen in MuseScore 2.x. I haven't tested other versions of the 3.x series for this bug.
Steps to reproduce:
- Set the palette view to "Advanced", as it seems necessary to trigger this bug.
- Expand the Clefs palette.
- Drag a clef from the palette into the score.
- Press F9 twice to hide and then show the palettes.
- Go back to step 3.
Result: After doing steps 3-4 a few times, you will no longer be able to drag a clef into the score, and other palettes will be broken similarly. The drag animation doesn't even start.