BUG: Left ALt doesn't work as BUCKET 3 anymore

This scenario is reproducible if you use Left Alt for Bucket 3 and then
switch to using Rigth Alt for Bucket 3, and then switch back again to Left
Alt for Bucket 3. Now Left Alt will fail to function as Bucket 3.

Failed to reset AltOnR to 0 when Alt Key is released.

Signed-off-by: Suriyan Ramasami <suriyan.r@gmail.com>