We should support enable-background. This is mainly neccessary to support other sourceGrapics for filters. But we should implement it in a way, so that we can also use it for SVG Compositing (in SVG 2.0) later.
We could use repaintRectInLocalCoordinates() of the renderer, where the attribute enable-background is set, create a ImageBuffer and continue further drawings on the context of this ImageBuffer.
Good idea. Though it is not easy.
(In reply to comment #2)
> Good idea. Though it is not easy.
Don't spend to much time at the moment on it. HTML has ti support it as well for Compositing and Blending spec. We will do it hardware accelerated from the beginning :)
We won't support enable-background. The property is deprecated and removed from Filter Effects. Instead we implemented the isolation property. However, accessing the back drop is still not possible yet. This will be the next step. Closing this bug for now.