Comment 1 for bug 1381891

The problem we have is we deliberately decided not to do any validation on the scopes API side and leave it up to the unity (even the shell plugin doesn't care much about what's inside the preview widgets).

The downside is in many cases scope author is clueless if widget doesn't show up or look as expected.

On the upside, support for new widgets can be added to the shell or existing widgets can be enhanced to support new attributes without affecting the lower layers.

Now, the problem of not having a clue as a scope author if something goes wrong is and important issue, so perhaps we should look for a middle ground. How about adding a simple validation and only output cerr warnings if we see something we don't know (and never throw, unless we find cases where we really know thw widget is totally broken)?