Sometimes we define complicated location rules based on different criteria. It’s quite easy to make a mistake. It would be greate if there was a preview below the rules showing all the posts matching defined rules.
I know it requires AJAX calls and a new WP_Query each time the rules are changed, so maybe the preview shouldn’t show up automatically. There could be a button “show preview” at the bottom.
And what about showing all of the terms that a field group may be attached to, or users, or options pages, forms, widgets, attachments and images?
If the developer did this he’d also need to deal with all the possible custom locations rules that people add.
Every post, user, attachment, widget (etc) would need to be queried and individually tested against the same location rule logic that’s used to display the groups on the correct edit page.
It’s not as simple as doing a single query to see where the field group will appear. That information is not stored anywhere.
I know it’s not a trivial task and it requires much more work than making a simple WP_Query. But still, it’s doable and it would be a great improvement, especially for new users who might not fully understand what these rules mean.
Remember that we’re in a “feature request” sub-forum, not in a “must-have features request” 🙂