The previous code would stop validating when an error occurred which
meant that when a page contained multiple errors, only the first one(s)
to be checked would appear in red.
Now, all the errors will appear in red.
https://bugzilla.gnome.org/show_bug.cgi?id=734472
When a configuration setting is wrong, set the entry or file chooser
that contains the incorrect information to be surrounded by red.
This makes it easier for users to find where the error was made that
disallows them to click the "Apply" button.
https://bugzilla.gnome.org/show_bug.cgi?id=734446
