Semantic Widgets

Once the Semantic Space framework is in place, a 'semantification' of GTK could be done, to make it expose the information inherent to the widgets on-screen in the semantic space - at least until most applications do it natively.

Usually, widgets will expose sufficient information to match their data with metadata on the disk (e.g. via Tracker). This way, queries such as "all the contacts shown in this Evolution addressbook window who also appear in this Pidgin buddy list window" might be done.

One or more special UI applications would be developed to make such queries easily.

The reverse could also be useful: a patch to GTK that would automatically render resources asserted in a special 'GTK ontology'. This would realize something akin to a declarative UI over the semantic space.