Steve,
I’m very sorry for the confusion caused here but I think I understand what’s up here and can help. A couple of things aren’t going quite right here but here’s how to fix it quickly:
1) That dialog isn’t modal (as it might look). It’s sitting in an editor so you can just ignore it for now.
2) Go to Help > CodeMix > Update License…
3) Select the “Enter Key…” link
4) Enter your valid Webclipse key and save it.
5) That should restore everything to its normal state. You may or may not have to close and reopen the editor that is housing the dialog you’re looking at.
Backstory:
Unintentionally, we released a confusing looking message that we’re working on fixing now. We’ll be updating both the wording to make it clearer as well as obvious that it’s not a modal dialog locking up the Eclipse UI. It’s really a dialog that’s “inside” just that single editor pane but it’s rather hard to tell that.
Thank you again for reporting this so we can recognize the confusion we’ve caused with it and address it shortly. And please let us know if you need anything else.