bug#18143: Vertical scroll bar does not work with Image files

[Angelo Graziosi]

Il 29/07/2014 14:02, Eli Zaretskii ha scritto:
> > Date: Tue, 29 Jul 2014 12:56:26 +0200
> > From: Angelo Graziosi <angelo.graziosi@alice.it>
> >
> > When an image file (jpg, png..) is displayed greater than the frame
> > dimensions, a way to explore it is using the arrow keys (up, down, left
> > and right).
> >
> > With the introduction of horizontal scroll bar, it is very nice to use
> > it in place of L-R arrow keys: the HSB works fine here!
> >
> > This does not occur with vertical scroll bar. It has the full height of
> > the frame and cannot be moved U-D. So the only way to explore the image
> > vertically is to use the U-D keys.
> >
> > I see this both with MSYS2/MinGW64 and Cygwin builds of Emacs trunk.
>
> What you see is due to the difference between the 2 scroll bars in how
> the size of the scroll-bar thumb is computed: in character units for
> the vertical scroll bar vs pixel units for the horizontal scroll bar.

But is this a bug? I would convert also the vertical scroll bar to pixel 
unit..