Use the LeftPictureRoot and TopPictureRoot properties to display a specified part of the form's background picture. By default,  the LeftPictureRoot and TopPictureRoot properties are updated as soon as the control moves in the form. The LeftPictureRoot and TopPictureRoot properties indicates in pixels the (top-left) corner of the TAB control relative to the form. These properties have effect only if the root object of the skin being applied to the control displays a picture. Use the Load method to load and apply a new skin file to the control. Use the Style property to apply a predefined style to the control.

The following screen shot shows the picture on the form ( the form has no other controls in ):

 

The following screen shot shows the TAB control in the form with no picture assigned to the root object of the skin:

The following screen shot the TAB control after we applied the same source picture on the root object of the skin ( Invoke the "Edit-Tab" item in design mode, Select the "Root" item, Select "Picture\Add New" in Background panel, and select the picture to be put on the root's background, Click the "Save", and close the designer )

In these cases, we have used the following picture to be put on the form's background as well as on the root object of the skin.