These are boolean attributes that correspond to the similarly named flags
in the object's gadget.flags field.  if the value passed with the
attribute is TRUE, the corresponding flag in Gadget.Flags is set.  If the
value passed with the attribute is FALSE, the corresponding flag in
Gadget.Flags is cleared.  See the <intuition/intuition.h> include file or
the "intuition gadgets" chapter of the amiga rom kernel reference manual:
Libraries for more information.