Widget designer, select control remains empty

Hi,

I am using thunder for creating widget designers for my custom mvc widgets. This has  always been working fine, however recently the select control dialog remain emtpy when i want to create a designer. I have tried cleaning and rebuilding the project (no errors there) i uninstalled en reinstalled thunder, but so far no luck. It seems something is preventing this dialog from being properly filled.

Is there some other cache directory that should be cleared?