When Ajax Update Panel is used in a page, mostly you will need to use XHTML doctype. Some of earlier Intersoft controls that are not designed for XHTML doctype, such as WebTab, will be displayed incorrectly due to the different styles rendering between HTML and XHTML doctype.
The layout issue in WebTab can be easily fixed to support XHTML by tweaking the default styles available in WebTab. For instance, removing padding, margin and overflow property from the FrameStyle will fix the main layout of the control.
With this workaround, you can use WebTab control along with its built-in features in XHTML pages without issues.
Hint: When complex image is used, you need to maintain and customize the style appropriately.
Please refer to the sample to see how it works.