For the "It also seems the Check for Updates... menu item crashes", are you referring to every now and again it just doesn't seem to do anything?

I found that the if/else code branch when version was up-to-date was not wrapping the call to display the alert in Platform.runLater() - So I've pushed a quick fix for that here

Do you want to take that as a separate fix?

Otherwise, given this is an enhancement, I am also seeing a lot of duplicated code that can probably be re-factored and I'm also not sure why all this logic needs to be in SceneBuilderApp anyway. Am I missing some design pattern or something (I'm very new to desktop programming in general and still finding my feet with Java and JavaFX).

I was thinking all the update logic could be rolled into an overhauled "About" dialog which I have some ideas about and was going to start a discussion topic on.

Am I going too deep with this?

For this issue, fixing the above two check boxes is sufficient. Visually, I'd probably go for a red dot / circle near "Update" in the menu bar to indicate that an update is available.

About and update dialogs should probably stay separate.

As for refactoring, I'm in the middle of #473 so don't worry too much about the architecture of existing code -- it will be updated.

OK. I see what I can do to add a visual indicator.