Disable backfilling of windows created with bg=none, which otherwise

would force a framebuffer readback.

--- ./composite/compalloc.c.spiffiffity	2006-03-13 16:59:55.000000000 -0500

+++ ./composite/compalloc.c	2006-04-12 16:37:50.000000000 -0400

@@ -478,6 +478,7 @@

      * Copy bits from the parent into the new pixmap so that it will

      * have "reasonable" contents in case for background None areas.

      */

+#if 0

     if (pGC)

     {

 	XID val = IncludeInferiors;

@@ -492,6 +493,7 @@

 			       w, h, 0, 0);

 	FreeScratchGC (pGC);

     }

+#endif

     return pPixmap;

 }