My "trick" didn't "work", unfortunately.
I wasn't able to actually get a 4.0 skin to run under 3.3. When I changed the registry paths to the 4.0 SkinInstaller, that 4.0 SkinInstaller launched the 4.0 Rainmeter.
Apparently Rainmeter itself doesn't register any filetype handlers, so you can't launch an arbitrary instance of Rainmeter when installing a skin with SkinInstaller, the instance that is launched is whatever instance is in the same directory as SkinInstaller
It is currently March 28th, 2024, 2:02 pm