Is there a native way to get a Common time signature (c) in an open meter piece?
Selecting “Common/Cut common” in the properties has no effect.
No, in this case you can’t easily do this. One option would be to change the default barline type for the flow to be the dashed barline on the Barlines page of Notation Options, then change the gap between dashed to be something sufficiently large in Engraving Options such that no barline actually appears.
This will work provided you don’t have any notes that need to cross barline positions, of course, as those will still end up being tied.
If you really need the music to behave as if it is truly open meter, your best bet would therefore be to use an open meter, then in Engrave mode open up some room for the initial time signature, and add it as text.
