Do not call gtk_tree_model_filter_set_visible_func() multiple times
Do not call gtk_tree_model_filter_set_visible_func() multiple times

Since there is no need to set the visible function more than once, do
it only once. This fixes some critical warnings.

Cordia/libhildon,android-808/libhildon,android-808/libhildon,Cordia/libhildon,android-808/libhildon,Cordia/libhildon