Which documentary was screened at Cannes, The World Without US or The Thorn in the Heart?
The Thorn in the Heart: The Thorn in the Heart (French: "L'épine dans le coeur" ) is a 2009 French documentary film directed by Michel Gondry. The Thorn in the Heart:  It was given a special screening at the 2009 Cannes Film Festival and was also screened at the Sheffield Doc/Fest.
i don't know