Subject: bug#18990: 25.0.50; Scroll bar display problems

From: martin rudalics <[email-masked]>
Date: Sun, 09 Nov 2014 12:56:14 +0100

> As I mentioned (quoted below), I was already convinced by seeing the
 > horizontal scroll bar partially cover the mode line.  But by using a
 > separate minibuffer frame (I suppose that's what you mean by removing
 > the echo area),

That's what I meant, indeed.

 > I do indeed see the analog with the horizontal scroll
 > bar of what I see with the narrowed vertical scroll bar on the right: it
 > is at the very bottom of the frame and cut off.  Quite convincing,
 > indeed.  Thanks for the suggestion.
[...]
 > I'm not sure I understand the distinction you're making.  By "slider" do
 > you mean what is sometimes called the "thumb" of the scroll bar?

IIRC GTK uses the term "slider" for "thumb".

 > (According to Wikipedia, a slider is a different kind of widget from a
 > scroll bar, but I didn't try checking other sources.)  If so, are you
 > saying that Gtk only controls the width (or height) of the slider
 > (thumb), while Emacs controls the size of its container, which I guess
 > is the scroll bar taken as a whole?

I think so.  Depending on the toolkit Emacs can control size, background
and borders of the container.  The GTK slider is controlled by the theme
though.  Jan will correct me.

 >> Another problem is that currently we prescribe a minimum width for
 >> scroll bars which has parts of the scroll bar background change
 >> appearance when the Gtk slider is narrower.
 >
 > Not sure I understand; can you elaborate or tell me how I can see what
 > you mean?

I once posted a screenshot here

http://lists.gnu.org/archive/html/emacs-devel/2014-01/msg02228.html

It might be related to the fact that we prescribe a minimum width of the
scroll bar in update_theme_scrollbar_width but I've not yet found a
reliable fix yet.  See also bug#17982.

martin