I'm not really able to pinpoint the cause of this, other than the fact
that I have a custom source provider which is firing off a source
changed event, and the workbench is locking up.
Bugs like 236612 and 244427 make me wonder if this is just another
symptom of a possible threading issue in the API.
Its also entirely possible that I'm unknowingly violating some contract
with how source providers are supposed to operate.
