That code lives in GNOME Control Centrer and it is not a widget. There is a GtkTreeView for the list and below it, there is a GtkToolbar with two buttons (using the symbolic icons list-add-symbolic
and list-remove-symbolic
). Instead of the GtkTreeView could be another widget, but the layout is the same.
You can see the glade files inside each panel
. For instance, User Accounts.