mdi z-order [was gtk accessibility on win32]

[Bill Haneman <Bill Haneman Sun COM>]

Allin Cottrell asked:
> Do you think it is essential to 
> produce a win32-specific backend to support mdi_zorder?  Will it 
> produce garbage if I just return 0 from that function?

If you don't implement anything 'useful' for mdi_z_order, mostly it will
break screen review.  That's the primary client use case for this API.

However I think win32 gives you a way to find out the z ordering of
overlapping objects (things in a canvas, or an 'mdi' frame, or the z
ordering of onscreen window frames).  Of the three cases, the Z order of
onscreen windows is probably the most important. But it would only
really be used for screen review or, possibly, determining the region of
interest for a magnifier.

- Bill