When using a Vertical Tab form group with required fields, if a field that is required isn't filled in, or skipped by accident, and another tab is accessed, the tab with the previously unentered required info doesn't focus, which can sometimes lead to confusion.
I've created a patch that will check for the first element it finds that is required and is invalid, and selects the correct tab, focusing it. I've tested this out and it seems to work well for the scenario.