The Add Connection widgets from the connection
editor dialog weren't properly using the available
space, since they don't expand.
Fix that by making them expand and fill the available
space properly. It also avoids blank space by vertically
centering the list.
Disable the type-ahead search in the connection editor, the
number of items, and their positional stability means that
a search feature isn't warranted.
As a precaution, also check the success of
gtk_tree_selection_get_selected() to avoid crashes.
https://bugzilla.gnome.org/show_bug.cgi?id=693685
This code is fairly independent of the rest, and we don't want
net-device-wifi.c to become too massive and unmaintainable.
The code in connection-editor/ is fairly similar to
nm-connection-editor, with some simplification because we
currently only edit wireless connections.
The code in wireless-security/ is almost a straight copy
of the same code in nm-connection-editor, with some changes
to the .ui files to make them fit better in the new design.
