Porteus

the kiosk edition boot in firefox full screen mode, but if I open a pdf with pdf.js from Firefox and I click on full screen button from pdf.js interface, then I click two times on back button from Firefox interface, the browser is presented in window and not in full screen with all the menus visible.

I think that should be added the parameters to lock the fullscreen mode of pdf.js. I add this in prefs.js

user_pref("plugin.disable_full_page_plugin_for_types", "application/pdf");

yes - i'm aware of this problem and even posted a bug report on their bugzilla but mozilla is giving it a low priority and willing to fix it sometime in the future:
https://bugzilla.mozilla.org/show_bug.cgi?id=864378

as you can see html5 fullscreen video playback is also affected and unfortunately it's not possible to disable it globally. you have to go site by site and it's not possible to cover whole internet. also - some users may want fullscreen so we cant disable it by default.

bug stays open till upstream fixes it.