Programming guideline of WinDom
To attribute an extended object, WinDom (actually the RsrcXtype()
function) scans the objects inside a ressource (or an integrated
ressource) and examines the value of ob_type :
- the low byte of this value is G_USERDEF, RsrcXtype() does
nothing, because it could be a special object reserved by the
developper,
- the high byte of this value is not null, it is an extended
type. RsrcXtype() gives a new type to the object (the G_USERDEF)
the real. Depending the extended type, RsrcXtype() attributes to
the ob_spec field a structure USERBLK containing the right
userdef function (this function will be called by AES to draw
the object) and the real object complet type (then changes done
by RsrcXtype are reversible).