Hellow,
dhtmlxtabbar is very cool except that the height attribute of a tabbar is not compatible with the doctype in strict mode. Can you do something ? Tested on sample called tab_100pc.html.
Thanks a lot 
The problem is not in tabbar code, but in the way how height defined in case of xHTML strict doctype.
Tabbar will reflect css height, so you need just to create correct HTML layout
Please check attached sample.
tab_100pc.zip (637 Bytes)
Yes thanks it works if I add your code in my css.
Can you add this code (or other generic code) in your default css for supportingÂ
strict mode in dhtmlxtabbar without any change ? It was done for other dhtmlx products :
dhtmlx.com/docs/products/kb/ … mal&q=1518
Thanks 
The problem is that changes necessary to correct work of tabbar will affect other DOM elements as well, while it is pretty safe, the situation is possible when such additional styling will cause effect on other on-page functionality.
Most probably we will not updated existing dhtmlxtabbar.css but will add alternative css for strict mode.