Certain XkbOptions in X11 would change keysyms for modifier keys between the key press and key release. For example, under the XkbOptions "grp:shifts_toggle", though shift keys remain Shift_L/R when pressed, they become ISO_Group_Next/Prev when released. This behavior makes devdraw unable to detect the release event correctly and as a result mouse button 1 click always interpreted as button 3 event after a shift key is used.

Fixes #347.

Fixes #54.

Fixes #339.

Need to think a bit more about locking, but overall it's a working devdraw. Multiclient mode may not be working but nothing is using it yet.