Re: 23.0.50; Cannot run calculator on TTY

[Richard Stallman]

    Presently, `split-window' has a problem with mode/header lines and small
    heights (presumably also with scroll-bars and fringes).  To check
    whether all windows are large enough after splitting it must make an
    assumption about the presence of these on the new window.  It currently
    bases its judgments on the appearance of the window that shall be split.

Strictly speaking, that is correct.  Splitting the window shows the
same buffer in both of the resulting windows, so it is valid if that
buffer could be displayed in both.  However, in a larger sense, given
that the aim is to display another window there, this does not really
DTRT.

One idea that occurs to me is that `window-min-height' could count the
header line, if any.  That way, the fact that some buffers have header
lines and others don't will not cause any problems for vertical
splitting of windows.  In the most usual cases, at least -- but not
in all cases, perhaps.

Another solution would be to pass a two buffers to `split-window',
telling it to select those two buffers, and to calculate based
on the assumption that those buffers will be displayed.