The SHEET control organizes TABS in the Extended UI using one of the following Tab Styles:

Default

B&W

Colored

Boxed

When you use the “Default” style, the SHEET/TAB control uses the OS lok and feel and inherits its colors from the Operating System Theme settings.  You can override this and utilize your own colors on SHEET/TAB controls by setting the checkbox “SHEET controls do not use the OS Theme color” as shown in the image below.  This template setting causes the PROP:NoTheme property to be assigned against all SHEET controls in your application.