Yeah yeah I know what you mean.
It is also implemented in Tizen and works good there.

I will take a look at it. Basically you need to hack around the window manager in sailfishos to accomplish this. Therefor I said it does not make sense fow now. The other point is the small screen size on the phone itself.
The most benefit I can see is on tablets because of their bigger screen.
But its on my todo. So I definitely will take a look. Though after this 1.0 release there are other projects that I want to complete first before I start working on new features