CSS Filters and Opera

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?