I'm not able to reproduce this with an empty entry point with only new MessageBox("Heading", "Message").show() (or with AlertMessageBox). Are you doing something more complex? If so, please post a code example that implements EntryPoint, and I'll try that instead.
Thanks for looking into this. It is funny, but I can't seem to reproduce it now. I tried everything I could think of when I had the issue.
I have tried simple entry points on the same machine. I believe when I got the issue, I was trying to pop up a dialog in a callback from a JSON RPC, and I see the code that I replaced it with -- I ended up just using an Info.display() and going on.
But now that I put the MessageBox() back in, it seems to work. Must have been something incorrect or transient in my environment.
I'll let you know if I see it again and will post code.