I've implemented the app manifest in #uxn, which effectively blocks me from sneaking undocument features since the key handlers MUST go through the menu tree.
Upon launching any app now, it will print the manual in the console, next step will be to draw the menu tree inside the application and make it navigable, a-la Macintosh.
I was partly reticent to moving ahead with this thinking it would be a pretty big overhead, but in the end it simplifies controls-routing a lot, and for a very little overall cost.
nasu.rom(before): 6586 bytes
nasu.rom(after): 6942 bytes