This prevents for example a d3d9 depth stencil from being destroyed when it
has no external references but is still in use by the device/stateblock. A
nice side effect is that it simplifies handling of "implicit" surfaces like
the frontbuffer and backbuffers, as well as the forwarding of reference counts
for surfaces that are part of a texture.
DDraw can draw to the front buffer only, thus there's never a Present
call which could pass this window. Due to that a drawing-independent
method is needed.
This is a long-needed cleanup aimed at removing the ddraw_primary,
ddraw_window, ddraw_width and ddraw_height members from
IWineD3DDeviceImpl, which just do not belong there. Destination
window and screen handling is supposed to be done by swapchains.
Henri Verbeet