linux: add support for check boxes
currently, getlantern/systray
calls gtk_menu_item_new_with_label
, which is why i think no check boxes appear when running on linux.
i think it needs to call gtk_check_menu_item_new_with_label
when the menu item data structured has checked set to true.
the reference manual for this is here: https://developer.gnome.org/gtk3/stable/GtkCheckMenuItem.html#gtk-check-menu-item-new-with-label
Edited by Kali Kaneko