The buttons should have a glassy transparent look. Also, they should not
be as tall, should light up on hover, and their labels should be white
in order to stand out. Making the labels solid white requires removing the
transparency set in modalDialog.js. Also, add a separate color setting
for the dialog as a whole - this avoids having a white icon.
https://bugzilla.gnome.org/show_bug.cgi?id=655428
dec55a3291
