drop shadow on multiply layer exceeds filter dimensions

[Konrad Roze]

I have object with drop shadow on lower layer and an object with drop shadow on upper layer.
Upper layer is composed via multiply operation.
Problem - drop shadow from upper layer influences drop shadow on lower layer outside of its filter dimension on upper layer.
(see the attached screenshot)
Seems that influence spans according to Multiply filter dimension.
However this seems wrong because upper shadow itself should not have any influence beyond its own filter dimension.

Im using Inkscape 0.48.4 on Win7 64b.

[su_v (suv-lp)]

Please attach the SVG file used for the screenshot to ease testing on different platforms with different versions of Inkscape.

[Konrad Roze (konrad-rozeslaniec)]

In attachment .svg to reproduce the problem.
Interestingly this is only appearing if there is no background.
Adding some background object helps, but obviously this is not a solution.

[su_v (suv-lp)]

Known limitation of SVG filter effects (SVG 1.1), see
"Double counting background"
<http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Filters-Compositing.html>

Proposing to link as duplicate to
- Bug #180890 “Page background is not an SVG element”
  <https://bugs.launchpad.net/inkscape/+bug/180890>