bug#32736: 26; Bind `C-x 5 2' to `clone-frame' by default

[Drew Adams]

> > Possible enhancement: Change default binding of `C-x 5 2' to
> > `clone-frame'.  Unlike `make-frame-command', `clone-frame' would use the
> > same frame-parameter values as the selected frame.  Here's a possible
> > definition of `clone-frame':
> 
> Hmm, how common is it to have a frame that doesnʼt have the same frame
> parameters as 'default-frame-alist', and you want to replicate them?
> Personally I quite like the current behaviour.

It's definitely the case for me. I use several kinds of special-display frames. 
If I use it on a *Help* frame get a *Help* frame (same background etc.). If I 
use it on an *info* frame I get an *info* frame, and so on.

If it's not the case for you then you should get pretty much the same behavior 
as now. I don't think you'll notice a difference.

> How about you make it take a prefix argument to get back
> 'make-frame-command' semantics (or keep the current ones, and add
> 'clone-frame' semantics to the prefix arg)?

Fair enough.

(defun clone-frame (&optional frame no-clone)
  "Make a new frame with the same parameters as FRAME.
With a prefix arg, don't clone - just call `make-frame-command'.

FRAME defaults to the selected frame.  The frame is created on the
same terminal as FRAME.  If the terminal is a text-only terminal then
also select the new frame."
  (interactive "i\nP")
  (if no-clone
      (make-frame-command)
    (let* ((default-frame-alist  (frame-parameters frame))
           (new-fr  (make-frame)))
      (unless (if (fboundp 'display-graphic-p) (display-graphic-p) 
window-system)
        (select-frame new-fr)))))