I've seen this requested in one form or another a number of times. I would love to be able to call an Action Group from within another Action Group. Failing that, be able to select a number of Action Groups (Shift and/or Control) Click and change their on/off status at once. The ability to move multiple selected Action Groups together would also be great.
Example of where it would be helpful to me:
I run a series of Actions, after I've used Web Sources, to clean up and normalize the tags (which actions depends on the web source(s) I've used on that album)
in Foobar2000 I apply ReplayGain on an Album level
Back in MP3Tag, I deselect all active Action Groups and select and run another with $rg2sc to copy Album Gain to Track Gain fields to fool Sonos which still doesn't read Album Gain in MP3 files.
Then deselect the $rg2sc Action Group and reselect all the others for the next album.
The first and 3rd step require different actions in MP3Tag, and it gets tedious and the process is error prone to select then deselect and reselect individually all the Action Groups I run. By grouping I'd have to toggle only two Action Groups in each run.
Thanks for the excellent software.