Panel Scrollbars and IE 7
When trying to get a panel to display dynamically in conjunction with the HoverMenuExtender, there are some issues with displaying the content while forcing a scrollbar using the overflow-x and overflow-y CSS styles. As a personal recommendation, to implement a vertical scrollbar for a panel, set the width and height for the panel appropriately, and set overflow-x: hidden and overflow-y:scroll in your style. This is what it took to implement scrolling for one of my projects.