[RFC] Fixes in GtkFontChooserWidget

[Alberto Ruiz <aruiz gnome org>]

Hello,

I have created a branch[0] with a few minor changes to GtkFontChooserWidget

One of the commits is a fix to solve a problem with smooth scrolling
in the slider.

The other one removes the value from the slider which is redundant
(and innacurate at times) wrt the value in the spinbutton.

I wrote this widget originally so I'm mostly certain I know what I am
doing but since I am doing UI changes I wanted to get someone
reviewing the code before pushing.

PS:

[0] https://git.gnome.org/browse/gtk+/log/?h=wip/fontchooser-fixes

--
Cheers,
Alberto Ruiz