These attributes correspond to one field in the object's embedded Gadget
structure--the GadgetText field.  Setting any of these attributes copies
the attribute's value blindly into the GadgetText field.  In addition,
setting GA_Text also sets the GFLG_LABELSTRING flag in Gadget.Flags and
setting GA_LabelImage sets the GFLG_LABELIMAGE flag in Gadget.Flags.  The
GA_IntuiText attribute must be an IntuiText pointer, as with old-style
gadgets.  GA_Text takes a pointer to a NULL- terminated string (UBYTE *).
GA_LabelImage takes a pointer to a (Boopsi) image.  Note that most gadget
classes do not support GA_Text and GA_LabelImage.  See the description of
specific gadget classes for more details.