bug#38181: Actual height of mode-line not taken into account

[martin rudalics]

> Thanks.  So the only thing that's missing is that it should call
> display_mode_lines, and then look at DESIRED_MODE_LINE_HEIGHT instead
> of WINDOW_MODE_LINE_HEIGHT?

I suppose so.  But please always keep in mind that the window code
does not handle problems caused by specifications in the mode and
header lines immediately.  For example, it will not auto-resize a
one-line window when its mode line height is increased to more than
its text height.  Try with a one-line window and Jonas'

(set-face-attribute 'mode-line nil :height 250)

>> Still, it will penalize every
>> ‘fit-window-to-buffer’ call (without a redisplay, though).
>
> Why "penalize"?

Because 'fit-window-to-buffer' now has to calculate the mode line
height which it didn't before and which for the majority of users
never changes.

martin