internal override void BlitFromOffscreen (IntPtr dest_handle,
Graphics dest_dc,
object offscreen_drawable,
Graphics offscreen_dc,
Rectangle r)
{
XGCValues gc_values;
IntPtr gc;
gc_values = new XGCValues();
gc = XCreateGC (DisplayHandle, dest_handle, IntPtr.Zero, ref gc_values);
XCopyArea (DisplayHandle, (IntPtr)offscreen_drawable, dest_handle,
gc, r.X, r.Y, r.Width, r.Height, r.X, r.Y);
XFreeGC (DisplayHandle, gc);
}