bug#16474: 24.3.50; `set-window-scroll-bars` has no effect after you set it once to zero

bug#16474: 24.3.50; `set-window-scroll-bars` has no effect after you set it once to zero

[Drew Adams]

emacs -Q

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

The scroll bar disappears.

M-: (window-scroll-bars) 

returns (0 0 nil nil)

M-: (set-window-scroll-bars nil 20)

has no visible effect.

M-: (window-scroll-bars) 

still returns (0 0 nil nil)

Toggling `scroll-bar-mode' any number of times also has no effect.

While I'm at it: a doc bug for `window-scroll-bars': There is no
description of any of these terms that are introduced, hence there
is no real description of the return-value: zero information, other
than it being a list of 4 elements):

WIDTH
COLS
VERTICAL-TYPE
HORIZONTAL-TYPE

For a function that *gets* some information, this doc string tells you
almost nothing about what that information is.


In GNU Emacs 24.3.50.1 (i686-pc-mingw32)
 of 2014-01-07 on ODIEONE
Bzr revision: 115916 bzg@gnu.org-20140107233629-du2solx6tmxnx0np
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/binary --enable-checking=yes,glyphs
 'CFLAGS=-O0 -g3' LDFLAGS=-Lc:/Devel/emacs/lib
 CPPFLAGS=-Ic:/Devel/emacs/include'

bug#16474: 24.3.50; `set-window-scroll-bars` has no effect after you set it once to zero

[martin rudalics]

 > M-: (set-window-scroll-bars nil 0)
 >
 > The scroll bar disappears.
 >
 > M-: (window-scroll-bars)
 >
 > returns (0 0 nil nil)
 >
 > M-: (set-window-scroll-bars nil 20)
 >
 > has no visible effect.

Obviously so:

Third parameter VERTICAL-TYPE specifies the type of the vertical scroll
bar: left, right, or nil.

You specified nil.

martin

bug#16474: 24.3.50; `set-window-scroll-bars` has no effect after you set it once to zero

[Drew Adams]

>  > M-: (set-window-scroll-bars nil 0)
>  > The scroll bar disappears.
>  > M-: (window-scroll-bars)
>  > returns (0 0 nil nil)
>  > M-: (set-window-scroll-bars nil 20)
>  > has no visible effect.
> 
> Third parameter VERTICAL-TYPE specifies the type of the vertical scroll
> bar: left, right, or nil.  You specified nil.

Oops.  Thx.  I will close the bug.