Idea Summary
It would be nice that the label / header of apex tabs are checked visible in red in some way just for indicating that this tab contains items with errors.

Use Case
Improve user experience when one of the tabs contains items with validation errors. If you are not placed on the tab with errors, you have to either click on every validation error message to automatically open affected item in corresponding tab, or manually go tab by tab searching for it.

Preferred Solution (Optional)
Check label or tab with a red color, * or similar behaviour.