better notification on publish confirmation screen

Our users have run into a use case that leaves them frustrated and perplexed. They have clicked the Publish button and the post editor changed the right sidebar to a publish confirmation, where they have to click Publish again to actually publish. However, the Publish button is not active and nothing happens when they click it. There is nothing visible on screen the explain why Publish isn’t working.

What has happened, of course, is that they paid no attention to the pink banner at the top of the editing area that reminds them to select a category. They saw it an hour ago when they started writing and have either forgotten about it or didn’t realize it was a commandment rather than a suggestion. It has long since scrolled off the screen, so they can see nothing on the screen to explain the failure to publish their post.

Can you please make a change to your plugin to display some sort of highly visible error message in the Publish confirmation UI to explain why publishing is not yet possible? It would save me getting phone calls from post authors at 10:45 PM. Thank you.