Renaming a screen control corrupts concert
MainStage v3.4.0, macOS 10.14
1) New concert, choose Keyboard template (or any, probably).
2) In Layout mode, select the vertical meter.
3) In the Screen Control Inspector, type in a different name e.g. "Foo".
4) Click away from the text box so the new name is set.
5) Save and close the concert.
6) Try to re-open the concert, fails with this error message: 'The document "testing.concert" could not be opened. The file isn't in the correct format. Please restore it from backup.'
Some screen controls such as the keyboard can be safely renamed, others such as vertical meter, vertical fader, expression pedal, etc. corrupt the concert as described.
MainStage, macOS Mojave (10.14)
