window: drop GtkStock

GtkStock is deprecated.

https://bugzilla.gnome.org/show_bug.cgi?id=705904

Signed-off-by: Yosef Or Boczko <yoseforb@gmail.com>
filter-manager: drop GtkStock

GtkStock is deprecated.

https://bugzilla.gnome.org/show_bug.cgi?id=705904

Signed-off-by: Yosef Or Boczko <yoseforb@gmail.com>