XkbKeysymToModifiers finds the set of modifiers currently bound to the keysym
ks on the core keyboard. The value returned is the mask of modifiers bound to the
ks. If no modifiers are bound to the keysym,
XkbKeysymToModifiers returns zero; otherwise, it returns the inclusive OR of zero or more of the
following: ShiftMask, ControlMask, LockMask, Mod1Mask, Mod2Mask, Mod3Mask,
Mod4Mask, and Mod5Mask.