bug#4543: window-full-height-p

[martin rudalics <rudalics@gmx.at>]

 > Why doesn't it make sense?  The computed value of new_frame_total_cols
 > is used to enlarge only the frame's root window:
 >
 >   if (new_frame_total_cols != FRAME_TOTAL_COLS (f))
 >     {
 >       set_window_width (FRAME_ROOT_WINDOW (f), new_frame_total_cols, 2);
 >
 > And for the root window, FRAME_TOTAL_COLS is correct, I think.  The
 > window configuration, however complex, does not affect the root
 > window, does it?

With Emacs -Q I can evaluate

(set-window-scroll-bars nil 0 nil)

to remove the scroll bar from the *scratch* window keeping the window
size unaltered.  When I now evaluate

(scroll-bar-mode -1)

the width of the frame shrinks and with it the number of columns used
for text in the *scratch* window.  This doesn't make sense.

 >> I'm not sure, however, whether text-only terminals inherently rely
 >> on these calculations.  So the question I essentially ask is whether
 >> the number of total columns of a frame's root-window invariantly
 >> equals the width of that frame over all possible terminals.
 >
 > I think it does, yes.  In any case, the code in change_frame_size_1
 > _is_ run on text-only terminals (or should I say for frames on
 > text-only terminals, since we have multi-tty now).

Fine.  I wasn't entirely sure about

   dos_set_window_size (&newheight, &newwidth);

which IIUC does adjust the width value via

   *rows = ScreenRows ();

so this eventually does get related back to the frame's root window.

martin