One idea I had is maybe you could apply a gradient to the top of the tabs... make sure it's kind-of like a semi-transparent gradient, though, so it's safe on different types of themes. My only complaint is that the tabs are too flat. Perhaps the menu at the top(where Save, Open, etc) could be reworked somehow to be "sexier". Too lazy atm to really give a direct example, maybe will revisit this post later to go into further detail.