RE: Is a method like this already in emacs?

[Drew Adams]

> now i wonder if a function that does the same is already available
> somewhere in emacs?

Yes, there is a similar command already: `mouse-tear-off-window'.
I bind it to `C-mouse-1' on the mode line:

 (global-set-key [mode-line C-mouse-1] 'mouse-tear-off-window)

Click `C-mouse-1' anywhere on the mode line of the window you want
to tear off into another frame.

Doc string: "Delete the window clicked on, and create a new frame
displaying its buffer."