I think the bug I'm seeing in my build process is caused by that modal
"No changes" dialog our update stream currently throws up.

To test this, I've written a near-stub HeadlessUIManager. A UIManager
indicates that it may be used by returning true from #isActiveManager.

I have two questions:

(a) How can I detect whether or not I'm running headless, from within the image?

(b) Given that MorphicUIManager class >> #isActiveManager returns true
if there's a World, and I'm not quite ready to set World to nil
because running headless is relatively unsupported, how do I make sure
that _this_ UIManager runs, and not _that_ one?

I'd expected a UIManager class >> #default: like ToolSet has. Or even
better, something based on a resumable exception.

Thanks!

frank