If you use the <j>/<k> keys to navigate down/up in your message list, the focus jumps down/up two messages, skipping one.
Regressions are P1.
GMail is Google.
<rdar://problem/4631576>
This could use better steps to reproduce. It's not obvious how to focus the message list at all, since clicking a message replaces the contents of the page with that particular message.
OK, I figured out this much: - When logged into Gmail, click Settings link - enable keyboard shortcuts and confirm Now there's a black angle bracket caret pointing at one of the messages in the list. Typing "j" or "k" will move the caret to a different message. However, I can't reproduce the bug. The caret moves one message at a time for me.
This bug is pretty old, and I can't reproduce it with tip of tree now that I've figured out the steps. I'm going to move this to worksforme, under the assumption that it was fixed sometime in the last few months.