- When moving a shaded window, the window sometimes unshades poorly and 
following error occurs:

 twin: X_ConfigureWindow(0x0): BadValue (integer parameter out of range 
for operation)

To restore and resize the window, there are two options: 
either maximize the window and then resize it, or right-click on the 
window while holding down the Alt button and resize the window that way. 
I believe that this bug is related to the masking operation, but haven't 
been able to hunt it down yet.

- The blank bar to the right of the button area does not accept 
double-clicks if you want to shade the window. For now, in order to 
shade a window, you need to double-click in the title area only.