Enabling backing store

[David Hagood]

Has any thought been given to enabling backing store on Wine's windows? 
As it stands now, when you obscure a Wine window, it forces the Windows 
app to redraw the screen. Many times this is not needed. Perhaps a 
configuration option to allow certain apps to have backing store on 
would be useful.

I know that up until a few months ago, it was possible to go into wnd.c 
and change the default from NotUseful to WhenMapped and things seemed to 
work well. However, the structure of the X driver has changed, and a 
simple patch is no longer possible.