Set a background pattern in a window
You use GETPIXPAT to get a properly-formatted handle to the ppat resource's data, and you use BACKPIXPAT to attach it to the current window. For example, the following fills a window with your desktop's pattern (which is System ppat #16):
Inside Mac says you should not dispose of ppatH& after calling BACKPIXPAT, because the window uses it, and that the system disposes of it for you when you close the window. It is not clear what you should do if you _switch_ from one pattern to another while the window's still open--I would think that in that case you ought to explicitly dispose of the (old) ppat handle after switching.
ppatH& = FN GETPIXPAT(16) '16 = desktop ppat
IF ppatH& THEN CALL BACKPIXPAT(ppatH&) ELSE BEEP
CLS 'This "Refreshes" the background
do something like this in your initialization function...
then when you get an update event for the window do something like this...
patRsrcNo = 5001
pat& = FN GETPIXPAT(patRsrcNo)
rgn& = [WINDOW(_wndPointer)+_visrgn]
CALL FILLCRGN(rgn&, pat&)