option to select all countries

the new select2 widget is great in most circumstances – but not so much when you need to be able to select a lot of options from the list. most notably, for sites that need all of the countries enabled, it's incredibly tedious to try to select them one by one from the select2 drop down. and despite the help text – deselecting all options does not enable all options (it just restores the default value of the United States).

I'd like to devise a simple way to quickly select all countries.