this is my updated patch for hadling svgelements referenced by id on the feImage filter primitive.
It is not working yet but is much better than the previous patch I sent to the list. Now the URIReference is properly handled and a NRArena/NRArenaItem created. Then I create a pibblock and render the svg element in it.
When I call the nr_arena_item_invoke_render method I get this error:
** (inkscape:6874): WARNING **: rendering element File display/nr-arena-item.cpp line 308 (?): Assertion item->state & NR_ARENA_ITEM_STATE_BBOX failed
I dont know how to get rid of this one. I am going to travel now and will be back only next week. If anybody wants to give it a try, this patch needs a last touch to get working.
(it also adds an extra button to the feImage settings UI: to use an element instead of an image, you must select the desired element and then click on the "SVG Element" button)
best wishes, Juca