You can customize the look of tabs as they use images.
Log in to the Portal Server management console.
Edit the display profile for the Developer Sample organization.
To edit the display profile:
Select Global Themes and the theme you wish to modify in the DP XML Tree.
Change the value of the tabNotchImage property to the new image name.
By default, the value for this property is tabNotch.gif.
Copy the new image into PortalServer-base/web-src/desktop/tabs/images directory.
Run the PortalServer-base/bin/psadmin redeploy --adminuser amadmin --passwordfile passwordfile --portal portal-ID subcommand to deploy the new image.
Reload the Desktop to verify the change.