About software cursor

Hi all,

I am now update a driver of XFree86. I met a problem that when choose to use s/w cursor, it seems has conflict with 2D acceleration.
The cursor always left a turbid cursor box after drag a window. It seems that the s/w cursor not update its background when 2Ds blt is worked. How can I resolve this problem? It seems we cant control a software cursor, and also has no 
Flags can set in ScreenToScreencopy routine. In the coming XFree86 4.2.99.3,
The ARGB cursor is done by the software if driver not support yet, so the the problem seems can't be avoid.

What can we do with this?

Thanks.