Comments #3 and #4:
1. new score
2. layout -> page settings
3. switch between mm and in and click 'apply' (not 'ok')
4. repeat 3 a few times
The margins keep changing for me.
Now try the above but with clicking 'ok'.
The margins change a few times, but then stop changing.
Default margins for new score are 10mm except for bottom, which is 20mm
Switching to inch, then back to mm causes the left and right margins to change to 8.5mm from 10mm.
Switching back to inch again displays the correct, original 10mm value in inches = 0.39in
But from now on, no matter how many times you switch back and forth inches to mm, it's 8.5mm for left and right margins, and the inches are correct, but out of sync with the mm.
Seems this affects 2.0.3 and current master 994090f.