Box notation / note frame support
I'd like to ask for the introduction of a feature consisting in being able to add a 'note frame' or 'note box' around a group of notes. Introducing this spanner element would eliminate the workarounds required for highlighting music* and writing box notation.
Graphically, there would be vertical lines drawn before the first note and after the last one, and two horizontal lines joining them.
By default the fill color should be transparent but both fill and border should be customizable for highlighting purposes.
The implementation of what I described would already be great, although further enhancements of this feature could include:
1) Adding an optional second spanner element, a centered horizontal line, which graphically would span from the end of the box to a later rhythmic position and end with a symbol (nothing/arrow/vertical line)
2) The repeated audio playback of the contents of the box until that centered horizontal line ends.
Frequency (many) - See the following requests
https://musescore.org/en/node/151191 (workaround in the comment by worldwideweary, attached image also taken from there)