bug#3949: 23.1.50; C-x 0 should go to a sister window if possible

[martin rudalics]

>  >    C-x 1
>  >    C-x 3
>  >    windmove-right
>  >    C-x 2
>  >    windmove-down
>  >    C-x 0
>  >
>  > For me it stops in the left window, not the right as I expect.
>
> Looks like a bug indeed.  It behaves this way in the current trunk but
> doesn't so in my Emacs.  I'll have to look into this.

OK the problem is with the following assignment in delete_window:

        /* Otherwise, try another window for SWINDOW.  */
        swindow = Fnext_window (swindow, Qlambda, Qnil);

This will fail to pick a useful window when deleting the bottom-right
window of a frame.  I use

        /* Otherwise, try another window for SWINDOW.  */
        swindow = Fprevious_window (swindow, Qlambda, Qnil);

which is better for me but fails miserably when deleting the
top-left window of a frame.  So maybe we need something like the
attached patch.  Could you try it?

martin

*** window.c.~1.639.~   2009-07-04 17:09:38.265625000 +0200
--- window.c    2009-08-01 15:06:48.906250000 +0200
***************
*** 1596,1602 ****
        if (!EQ (window, pwindow))
          break;
        /* Otherwise, try another window for SWINDOW.  */
!       swindow = Fnext_window (swindow, Qlambda, Qnil);
  
        /* If we get back to the frame's selected window,
           it means there was no acceptable alternative,
--- 1596,1605 ----
        if (!EQ (window, pwindow))
          break;
        /* Otherwise, try another window for SWINDOW.  */
!       if (NILP (XWINDOW (swindow)->prev))
!         swindow = Fnext_window (swindow, Qlambda, Qnil);
!       else
!         swindow = Fprevious_window (swindow, Qlambda, Qnil);
  
        /* If we get back to the frame's selected window,
           it means there was no acceptable alternative,