A different color appears in the unused screen lines

A different color appears in the unused screen lines

[Richard Stallman]

When I put this in .emacs

(custom-set-faces
  ;; custom-set-faces was added by Custom -- don't edit or cut/paste it!
  ;; Your init file should contain only one such instance.
 '(default ((t (:stipple nil :background "DarkSlateGray" :foreground "wheat" :inverse-video nil :box nil :strike-through nil :overline nil :underline nil :slant normal :weight normal :height 135 :width normal :family "adobe-courier")))))

the specified colors appear, but empty areas of the screen--those
beyond the last character on the line or in the buffer--come out in a
different color, a little lighter than DarkSlateGray.

I did M-x list-faces-display, and I saw that no face had a background
equivalent to the color of those empty areas.

I tried substituting a couple of other background colors.  I tried
"black" and "blue".  In those cases, the problem did not happen:
the screen appeared black or blue down to the end.

Does anyone know where that color is coming from?  I tried to study
the display code to figure it out but I can't find it.  I suspect that
the cause has to do with what GC is specified when x_clear_end_of_line
runs; does anyone know where that is specified?

Re: A different color appears in the unused screen lines

[Gerd Moellmann]

Richard Stallman <rms@gnu.org> writes:

> When I put this in .emacs
> 
> (custom-set-faces
>   ;; custom-set-faces was added by Custom -- don't edit or cut/paste it!
>   ;; Your init file should contain only one such instance.
>  '(default ((t (:stipple nil :background "DarkSlateGray" :foreground "wheat" :inverse-video nil :box nil :strike-through nil :overline nil :underline nil :slant normal :weight normal :height 135 :width normal :family "adobe-courier")))))
> 
> the specified colors appear, but empty areas of the screen--those
> beyond the last character on the line or in the buffer--come out in a
> different color, a little lighter than DarkSlateGray.
> 
> I did M-x list-faces-display, and I saw that no face had a background
> equivalent to the color of those empty areas.
> 
> I tried substituting a couple of other background colors.  I tried
> "black" and "blue".  In those cases, the problem did not happen:
> the screen appeared black or blue down to the end.
> 
> Does anyone know where that color is coming from?  I tried to study
> the display code to figure it out but I can't find it.  I suspect that
> the cause has to do with what GC is specified when x_clear_end_of_line
> runs; does anyone know where that is specified?

I believe setting the background color of the default face sets the
frame's X window background color via frame parameters.  The function
x_clear_end_of_line uses XClearArea which doesn't use a GC; it clears
with the X window's bg color.

Re: A different color appears in the unused screen lines

[Richard Stallman]

    I believe setting the background color of the default face sets the
    frame's X window background color via frame parameters.  The function
    x_clear_end_of_line uses XClearArea which doesn't use a GC; it clears
    with the X window's bg color.

That mechanism sounds like it ought to work, if all the parts of it
are really functioning.  Do you know how we can diagnose this any
further?

Re: A different color appears in the unused screen lines

[Gerd Moellmann]

Richard Stallman <rms@gnu.org> writes:

> Do you know how we can diagnose this any further?

I'd look at the function setting the bg color of the X window,
x_set_background_color (?), and see what it uses to translate a color
name to a pixel color.  If the bg color of the face is different from
the bg color of the X window, there should be a difference to what
faces do, which is found in load_color, IIRC.