Possible bug
I started using WACUP recently but I noticed a weird behavior while trying to set some Global Hotkeys that I always used with Winamp 5.666 and other previous Winamp ersions without any problems.
When I try to use the combination of ALT+anything (a few hotkeys I tried: ALT+1, ALT+S, ALT+numpad 3) for the "Playback: Stop" function, WACUP doesn't show any error and allows this combination, but when the music is playing, it just won't stop the music when using those hotkeys. If I use literally the same combinations (ALT+1, ALT+S, ALT+numpad 3) for "Playback: Play" or "Playback: Pause", it works normally.
I tried replacing ALT with CTRL and use the same combinations for the second key (CTRL+1, CTRL+S, CTRL+numpad 3) for "Playback: Stop" and it works normally. Even CTRL+ALT+anything works. It just won't work with ALT+any combination for some weird reason.
I even used Hotkey Screener to see if another program was using those hotkeys, but it said wacup.exe was the "owner" of the hotkeys using ALT+something, so it appears to WACUP is not saving or blocking the use of ALT+anything for the "Playback: Stop".