...but mouse button presses are laggy or ignored (win 10 build 10122). I tried messing with the mouse options, and it seems that turning down the UBS ...
Yep, I've confirmed that this is an issue with plain old MAME as well. I tested the latest windows 64 binary from mamedev.org and have the same issue ...
I've had problems with MAMEUI64 and 32 versions .1357 through .159 where the mouse does not function within games. Works in the UI, works in the game ...