MS3 - Grace note customization via PRE

It turns out that if you want other than the default fraction of the main note that MS assigns to an appoggiatura or grace note (which for me is more often than not for appoggiature in Baroque music), you can customize exactly the durations (and consequent positions) you want (including multi-note "slide" ornaments) by careful but reasonably straightforward manipulations in the newly-usable Piano Roll Editor -- and there is no other way. This should be documented with "Grace Notes" and/or the PRE. I'll contribute such documentation with an example if you want.