Page Settings, Apply to All Parts glitches
1) Open the attached score (don't worry about how weird it looks, it's for animating a drum machine).
2) File menu, Parts... New All, then OK. That will generate tabs for the score and 11 parts.
3) Format menu, Page Settings..., change portrait to landscape (any change will do)
4) Click the Apply to All Parts button.
5) In Ubuntu, on my i5 desktop, the dialog disappears behind the main MuseScore application window for several seconds, and the OS flashes a "MuseScore is not responding, do you want to force quite or wait?" message, then the dialog reappears and all is normal.
In Windows 10, on the same desktop machine, the MuseScore taskbar icon blinks a few times, and the dialog is frozen while it processes. Not nearly as bad as Ubuntu.
The button works, but it can scare a user, and on Ubuntu might even cause the user to force quit the MuseScore app. The attached score is not that big. 11 staves is not that many. This is probably worse with bigger scores.