I understand and appreciate your concern. We investigated if we could support tabbed browsing. We found that the level of effort required was excessive. The way that IE handles tabs is complex making it very difficult for us to detect and work with pop-up browser windows (i.e. tabs). We concluded it wasn't worth the effort that would be required to work with IE's tabbed browsing mode.
the Telerik team
Check out Telerik Trainer
, the state of the art learning tool for Telerik products.