1/2 wined3d: add helper function for retrieving front buffer coordinates

[Henri Verbeet]

On 23 March 2010 14:14, Roderick Colenbrander <thunderbird2k at gmail.com> wrote:
> +    IWineD3DSwapChainImpl *swapchain = (IWineD3DSwapChainImpl *) This->container;
That cast isn't safe unless you already know the surface is on a swapchain.