This feature has been implemented! :)
Released today in Espionage 3.6:
https://www.taoeffect.com/blog/2014/07/major-advancements-in-deniable-encryption-arrive-in-espionage-3-6/
Released today in Espionage 3.6:
https://www.taoeffect.com/blog/2014/07/major-advancements-in-deniable-encryption-arrive-in-espionage-3-6/