annoying limitation to 4 keyboard layouts

Like the most recent GNOME desktops, there is a limitation to setup only 4 keyboard layouts to choose from. This is annoying for us who use more than four languages. I know that in Fedora 18 this has been resolved. Also there it is possible to switch by choosing keybindings for previous and next layout in the list, which is very practical because there is no need to shuffle the whole list. Is it possible to port this code to Trisquel GNOME desktop? If I would like to do it on my computer how could I proceed? Thanks.