Obviously stupid user behavior 
, but selecting a bunch of tracks including master & sends gives:
By the way, I’m using this tool in combination with the ‘split into separate tracks’ script ( Split into separate Tracks | Renoise → works in 2.8 if you update the api version to 3.0 in the manifest yourself). And would love if I could split a track into a group, ideally have the dsp/vst-effects be copied to the group channel.
Could you create a variation of your tool that collects all the used dsp/vst’s from the different tracks on to the ‘master’ group channel, ideally keeping automation in tact??