Hi,
That looks good, except the following line presents me with a problem: "A UI MUST specify its
class in the RDF data, in this case ui:GtkUI. The class defines what type
the UI is, e.g. what graphics toolkit it uses."
This wouldn't be a problem if ui:QtUI were defined somewhere, but the only class which is a sub-class of ui:UI is ui:GtkUI. This seems to be the exact same problem that I mentioned was being discussed here: http://lists.lv2plug.in/pipermail/devel-lv2plug.in/2010-March/000491.html
That discussion didn't seem to have a resolution, and I could find any extension or code output as a result of that, except a simple qt to gtk and gtk to qt embedding demo.
Jeremy