MOUSESTATE mx,my,b1,b2 reports b1 as 1 whether b1 OR b2 is pressed. The value for b2 is never returned. This is in Windows 8.XX using version v12.656 and up (inc. 14.095). V10.XX does not have this issue.
GLOBAL mx%, my%, b1%, b2%
WHILE TRUE
MOUSESTATE mx,my,b1,b2
PRINT b1+" "+b2, 20, 20
SHOWSCREEN
WEND
This is definitely appears to be a GLB issue and not Windows 10 as per thread title.