For instance, I'm very thankful that my text editor and terminal allow me to split panes within their window rather than through multiple instances handled by the OS. I seem to prefer having panes/tabs vs window instances when alt-tabbing. Especially if I have two browsers splitting my viewport and a couple full sized browsers. This makes it very annoying to alt-tab only between the two half screened browser windows. On OS X anyway.
I actually tried using OS X's full split screen, but that creates a new virtual desktop. And even with reduced motion (which helps a lot avoiding headaches when working on multiple windows), it's still too slow/animated for me to switch between my virtual desktop with split screen browsers and other virtual desktops with editors/terminals etc.
Finally, what's nice about split panes vs window instances is resizing. Resizing one pane resizes the others. Whereas resizing one window does not resize the others (at least not on OS X's default floating windows. But even something like Spectacle. Someone knows of a tiled window manager that resizes all windows when resizing one btw ? Looking for something like dwm for os x)
Isn't that an argument for better window management, not redoing it in a slightly different way in every single application?
Of course, putting better window management in the OS would require the OS to offer hooks for 'new tab' etc, and then all the applications would have to be changed to use that facility instead of their own, which isn't particularly likely to happen any time soon.
While you have a point, I think there are plenty of examples where application managed multi-panes are useful.
* Emacs (and other text editors)
* IDEs
* Terminals
* etc...
Man, if I found a browser that gave me expressive enough keyboard shortcuts to make using a mouse optional (like Emacs) I would be switch to it in a heartbeat. Heck, Emacs style pane management and buffer switching might be enough.
