bug#20569: 24.5; Vertical scroll bar is shorter than frame in info buffer

[N. Jackson]

At 12:15 -0300 on Thursday 2015-05-14, Eli Zaretskii wrote:

> If the scroll bar extended past the header line, users would expect
> that line to scroll, which it doesn't.

Well, the scroll bar extends past the header line in the other programs
I mentioned (Spreadsheets, file managers) but those header lines don't
scroll.

> Anyway, this is how the header line was designed and implemented in
> Emacs.  We have tabulated-list-mode for the other kind.  The Info
> reader uses the header line for a good reason: it shows there stuff
> that needs to be always visible, so it cannot be the first line of the
> buffer, or behave like one.

Fair enough. It is a very minor blemish, and obviously not worth the
investment of effort to fix (if "fix" is even the right word).

In the game of Mah Jong, one must take the most scrupulous care while
building the wall to ensure that all four sides meet exactly and there
are no gaps. Otherwise it's terribly bad luck or evil spirits will get
in or something. (I forget exactly.) It is in a similar vein of
superstition, perhaps laced with a touch of compulsiveness, that it
disturbs me seeing a gap in the border of a window/frame!

I would like to work around the problem in my personal settings -- I
feel that should be possible by simply changing the colour of the header
line to match the colour of my windows -- but after some attempts at
this I was not completely successful.

I customised some faces to use the same background colour as my
windowing system widgets (gray94) (with readable foreground colours):

(custom-set-faces
 '(header-line ((t (:inherit mode-line :background "grey94" :foreground "black" 
:box nil))))
 '(info-header-node ((t (:inherit info-node :background "gray94" :foreground 
"black"))))
 '(info-header-xref ((t (:inherit info-xref :background "gray94" :foreground 
"navy")))))

So far so good. Now I don't have a disturbing gap in my window/frame in
Info which is great. (Not sure if there'll be a problem with the header
line in other modes, but I can tweak those as I notice problems.)

Unfortunately, another issue arises. The breadcrumbs at the top of the
Info buffer now have the wrong background colour!

The breadcrumbs seem to also use Info Header Node face and the Info
Header Xref face. It seems inappropriate that they should use Header
faces since they are not in the header. Is there a way to prevent them
from doing so?

Thanks.