Original commit message from CVS:
* sys/ximage/gstximagesrc.c (gst_ximage_src_start,
gst_ximage_src_ximage_get):
* sys/ximage/gstximagesrc.h (last_ximage):
When using Damage actually keep the last frame, and not assume
that the buffer we get already has the last frame on it.
Copy the cursor over if we specify a non-zero start x and
start y.