As far as modular GUI goes, I offered a few suggestions in this thread:
https://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=838007#Post838007

The idea is customizing existing Mixer Tab group panels to include just those things that user wants. User should be able to "detach" each tab and use it as it's own "floating" non-modal entity. Either reposition on single screen or move to secondary screen. Similarly this approach can be done for more compact tools like Shots, Holds, Rests, Partial regeneration dialog - combining existing two(!), Micro Chords, etc.

For most of other items, large size Tab groups. I was glad to see Songs, Patches and Titles added to MTP, but it saddened me that "Lyrics" and "Chords" were added in same group. These do not belong in library. In my view, if PGM liked the tabbed idea, they should of build on that and have separate clusters of tabbed items. To future proof the idea, it should be made modular. For example any two or more items could be made into one tabbed cluster, as I shown in this video:

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