- 
        depth 
      
- 
        The depth of a window or pixmap is number of bits per pixel it has.
        The depth of a graphics context is the depth of the drawables it can
        be used in conjunction with for graphics output. 
      
- 
        descendant 
      
- 
        If W is an inferior of A, then W is a descendant of A. 
      
- 
        device 
      
- 
        Keyboards, mice, tablets, track-balls, button boxes, and so forth, are
        all collectively known as input devices. The core protocol only
        deals with two devices: the keyboard and the pointer. 
      
- 
        direct color 
      
- 
        A class of colormap in which a pixel value is decomposed into three
        separate subfields for indexing. One subfield indexes an array to
        produce red intensity values, the second subfield indexes a second
        array to produce blue intensity values, and the third subfield indexes
        a third array to produce green intensity values. The RGB values can be
        changed dynamically. 
      
- 
        dispatching an event 
      
- 
        The process of finding the appropriate contact and its actions. 
      
- 
        double-click 
      
- 
        A sequence of two clicks of the same button in rapid succession. 
      
- 
        drawable 
      
- 
        Both windows and pixmaps can be used as sources and destinations in
        graphics operations. These are collectively known as drawables.
        However, an :input-only window cannot be used as a source or
        destination in a graphics operation.