Comment 2 for bug 512834

> However, it's quite cumbersome. One needs to create the filter,
> open the XML Editor, find the filter, note its id, find the layer,
> and then add "filter:url(#id)" to the layer's style attribute.

This process can be simplified somewhat (as interim solution):
1) open XML Editor
2) select the layer you want to add a filter effect to
3) return focus to the main window (while keeping the selection)
4) apply filter (either from the menu with presets, or via Filter editor dialog)
5) deselect current layer (<esc>) and select an individual object on that layer
   (to make sure that the current drawing level is a layer, and not the parent 'root' element).

done.