The tab order was improved on r52465 for the subject field (see T21342: LiquidThreads tab order is confusing), but it is still not good for the summary field:
- Open https://translatewiki.net/w/i.php?title=Support&useskin=vector
- Reach the first message you can find
- Click the dropdown menu next to it and then "edit"
I. Observed: The cursor is in the main textarea
- Tab twice
Pressing TAB should go to the wpMinoredit checkbox (not to the search box), after the edit summary.