I found that very interesting. This is something that webOS actually handled more or less (barring lots of bugs), e.g. a browser window opened by a program would stack on top of that program, instead of stacking on top of the "web browser" stack. E.g. note: http://cdn.slashgear.com/wp-content/...-webOS-2.0.jpg Note how the onion.com web browser is on the same stack as the mail message that opened it. Note how the web browser windows are unaffected. Same thing if you clicked on a "mailto:" link on the browser window. A new "compose mail" window would open in the current stack. The other mail windows would not be interrupted. And you could switch to different stacks and even different cards in the same stack by swiping. I for example think that the current multitasking implementation is completely broken on Sailfish, among other things because you can't open a new "compose mail" window without closing the older one. And as usual, iOS, Android, and the rest of the bang are even worse in this regard. webOS would be my without a doubt my favourite mobile OS ever if it wasn't for the entire... webOS thing. Although maybe that's the reason implementing proper multitasking was trivial to them.