Bitmap or custom images are used as imagery for a gadget by setting the
GFLG_GADGIMAGE flag in the Flags field of the Gadget structure.  An Image
structure must be set up to manage the bitmap data.  The address of the
Image structure is placed into the gadget's GadgetRender field.  The
bitmap image will be positioned relative to the gadget's select box.  For
more information about creating Intuition images, see the chapter
"Intuition Images, Line Drawing, and Text."  For a listing of the Gadget
structure and all its flags see the "Gadget Structure" section later in
this chapter.