True, really it should be the window managers job to provide tabs. I think browser tabs came about because people wanted many browser windows open and the windo

True, really it should be the window managers job to provide tabs. I think browser tabs came about because people wanted many browser windows open and the windows desktop was not really providing an ideal user experience, so the browser vendors said "fine we will do it our self". But really, if done correctly every application could be tabbed, and the application would not have to do anything.