From what I've heard, AROS's UAE patches the Amiga Kickstart ROMs at startup to enable native AROS code, which as well as speeding up window functions, allows window and menu integration and other cool features.
I was wondering if the kind of VM integration features I detailed above (if open source) could provide a possible "back door" towards implementing window (and screen) integration in WinUAE, with a closed-source and undocumented RTG.
Toni, I greatly appreciate the hard work you put into WinUAE, but never say "not possible".