- 
        undefine-keysym, Function
      
- 
        unexpected-reply,
        Condition 
      
- 
        ungrab-button,
        Function 
      
- 
        ungrab-key,
        Function 
      
- 
        ungrab-keyboard,
        Function 
      
- 
        ungrab-pointer,
        Function 
      
- 
        ungrab-server,
        Function 
      
- 
        uninstall-colormap,
        Function 
      
- 
        unit, Slot of
        bitmap-format 
      
- 
        unknown-error,
        Condition 
      
- 
        :unmap-notify,
        Event Type 
      
- 
        unmap-subwindows,
        Function 
      
- 
        unmap-window,
        Function