fix crash on close tab when ledger lines in the score
possibly fix crash on closing score
fix one more crash in fret diagram properties
remove contextual help button on Windows
fix #19985 - mark score dirty

after chnages to Menu -> Display -> Show
{Invisible|Unprintable|Frames|Page Margins}
Merge pull request #205 from Jojo-Schmitz/issue_#19985

fix #19985 - mark score dirty
small capitalization fix
add 'show staff' to palette cell properties
add missing gui update after deleting palette cell delete
rework of palettes & workspace
revert previous commit
fix some strings
hide lilypond export behind experimental command line option
clear selection should also clear start and end segment
more workspace changes