Anjelina, Not tabs per say but the viewer does allow for widget grouping (not in app builder though). All you have to do is look in the viewer documentation for widgetgroup. http://resources.arcgis.com/en/help/flex-viewer/concepts/index.html#/Widget_Container/01m30000000300...Adding tabs to the GP Widget is not something that is practical for your skill level and I have not had the need to do this so I have no code to share.Also there are many people on these forums that can provide answers so avoid addressing your questions to one individual if possible.PS. you still have other threads that have been answered and yet not marked as answered.