Restricting GNU Emacs to have only one modeline

[martin rudalics]

> Can I restrict GNU Emacs to have only one modeline. That is, configure
> GNU Emacs such that only the bottom modeline shall be shown. It won't be
> split even if the window is split. The details of the focused window
> (enabled modes, buffer-name, etc.) shall be shown in the only available
> full width modeline at the bottom of the frame. Also, each new window
> shall be split horizontally by a narrow line (as it is done vertically).
>
> I wish to have this so that I can save some lines when splitting window,
> especially in gdb-many-windows on my small screen. Also, I can include
> more details in modeline (like time, battery %), etc, that won't go
> hidden when I split-window-right.
>
> If it is possible, Please let me know how to implement this.

It's not generally possible since the presence/absence of the modeline
is buffer-specific.  Suppose you have a "normal" frame with one "normal"
window such as the one you get via emacs -Q:

(1) If the window has no modeline, then your frame has no modeline and
    your one modeline per frame invariant is violated.

(2) If the window has a modeline, then C-x 2 and C-x 3 will show a
    modeline in the new window too and again your invariant breaks.

So you cannot show the same buffer twice on the same frame and have only
one modeline on that frame.

To show a "narrow line" between two windows split by C-x 2 customize
window dividers.

martin