Lately I’ve had a few users respond on my CSS Tooltips post about it not working correctly in Opera, so I decided to investigate myself.  I looked at the example I created and sure enough, it tries to work, but fails.  My first suspect was the :hover css filter since this is what the css tooltips are based off of.  Then I decided to do a few tests with Impromptu.  My test was to use the :focus selector on the focused button to change the background color in one of my themes:

div.jqi button:focus{ background-color: #31B639; }
div.jqi button:focus:hover{ background-color: #21a629; }

Just as I suspected it worked like a champ in Safari and Firefox, but Opera had trouble.  It would flicker when I hovered over the focused button, but would not return correctly.  I did a few quick google searches but come up empty.  Anyone know if this is a known issue?