🚀 go-pugleaf

In playing around with GEM, I tried replacing the desktop (from
within an application) with a Degas Elite picture by:

1. defining the picture as a BITBLK data structure

2. placing the BITBLK data structure into an object data
   structure where:

     OB_TYPE=23  (G_IMAGE)
     OB_SPEC=pointer to the BITBLK structure

The replacement worked OK, but in object redraws, the mode is
transparent and I cannot see from my documentation how to get
into the replace mode. Windows, accessory images, etc, leave
ghosts on the new desktop.

If I use a GEM object like a G_BOX, the OB_SPEC lets me set
either transparent or replace via the OBJECT COLOR; when I set
replace, redraws eliminate the ghosting.

How would I set redraws to replace mode if I am using a G_IMAGE
object spec? OBJC_DRAW does not have a parameter to set.