With the recent developments regarding
ML emulation in QEMU, it's possible to generate visual diffs of ML interface (automated). This could highlight changes in menu, overlays, or even run automated self-tests for ML in order to spot bugs.
Proof of concept: I've renamed some menu items just to check how it would look like.

The script used to compare the two images:
compare a.png b.png -compose src -highlight-color yellow - | convert - -morphology Erode:2 Disk:5 -negate diff.jpg
composite a.png -compose Plus diff.jpg x.jpg
composite b.png -compose Plus diff.jpg y.jpg
montage x.jpg y.jpg -geometry 50%x50%+5+5 z.jpg
Interested in integrating this tool on the nightly builds page?
The biggest advantage IMO will be that you will no longer risk downloading untested builds; they will be self-tested. Of course, only on the feature subset that runs in the emulator, but still, much better than nothing.