Hi,

When your item doesn't have any sub items, no "sub menu" will be displayed at all. So the "empty space" that you saw is not even part of the TabStrip, thus there is are no option on the TabStrip can change the color of that region.

There are two ways around this. One way is to always create a fake child item. That way the sub menu will always be displayed so that the sub menu region will always look consistently. Note you will need to set your fake tab item to have the same Normal and Hover style and no text at all so that user won't see the fake item at all.

The second approach is to adjust the containing element's style. For example, if your TabStrip is placed inside the DIV, you can change your DIV's background color so that when the sub menu is not displayed, user sees the DIV's background color. If your first row and second row have different background color, you can use a background image on your DIV and set the image's position accordingly. The idea is you do it outside of the TabStrip, not on the TabStrip.

Hope this helps.

Thanks!