System lines - couple of bugs

Thank You for adding System lines!

It has couple of (minor) bugs:

A) if parts are already created, system line doesn’t appear in all parts
Create parts.
Add line.
Change it to system line. (tick “System Text Line”)
It is not in all parts. (You need to recreate parts, to be there)

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B) unchecking “System Text Line” doesn’t change it back to staff line
Create line on second staff.
Tick “System Text Line”. → it will move to the top of system (OK)
Untick “System Text Line” → it remains at the top. (Is it Staff 1 line now? No)
Create part → You can see, it is nowhere

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C) Undo doesn’t work (probably same problem as B)