Imageclass defines several methods of its own which subclasses of
imageclass either have to implement or pass on to their superclass. The
method IDs for imageclass are defined in <intuition/imageclass.h>.  Each
method requires some parameters.  The MethodID is the only parameter
common to each method.

 im_draw       im_hittest        im_eraseframe      im_move 
 im_erase      im_drawframe      im_hitframe        im_framebox