This feature doesn't seem to be implemented:
neither doe I get filter gadgets when adding e.g.
"filter=superseder" to the URL nor does
"superseder=1" have any effect (I can even
request garbage).

Any plans (or ideas) how and when to add
this? It might be less useful for superseder,
but I have a customized scheme where a multilink
links to all products which are affected by an issue.
Finding all issues of a product would be useful.