Only works on the message thread in Windows? If so could it be mentioned in the documentation 
Pretty much all GUI related functions only work in the message thread. (Not Windows specific either, I think…)
If you can use C++11, MessageManager::callAsync can be a quick solution for these situations.
Yeah - I’ve done it like that. Fixed. It took me a while to spot that that one wouldn’t work … didn’t help that some users reported it was working