Ahh! I see.
So the flickr tab is pulling an iframe from flickr.com which has an embeded flash. To IE flash should go on top of everything. So when you hover over the tab to expand out, the mouse instantly leaves the tab and goes above the flash content. Normally you can add a transparent parameter to the flash which would fix this, but since it is nestled in an iframe it is out of my control. I made a workaround for the flickr which is to not use the flash or iframe and use just static images. It is not as flashy, but atleast doesn’t cause the jitter or bouncing.
When the tabs are all the way out there is a blank area that extends the tab content past the next tab to keep if from being hidden. It is just an empty area with a defined width. IE sees it and thinks that since it is empty it doesn’t need to be shown, hence the content not sliding out past the next tab. I added a height and transparent background to that little blank buffer so that IE won’t disregard it and should push past the next tab.
Please update, yet again, to v5.15 and let me know if this solves the issue. Thanks again!