It's possibile to access (in read-only mode) to a value stored in a "about:config" property from an "unprivilegied" (as in: loaded from a http:// ... /something.html) script?
More specifically, I see the next ff (19?) will enable by default the "feature" click-to-play (see here for a description).
Is there a way, programmatically, to know in advance if the flag is true on the browser? We use a custom plugin and need to handle a custom "popup" to instruct the users about the feature and how to whitelist. And no, my users aren't savy enough to recognize the default ff "blocked plugin" logo in the upper right corner of the address bar)