I don't know anything about coding Firefox extensions, but in a general sense you can certainly set a timer to do something if your event handler isn't called within a certain time. Something like this.
It is better to add a progress listener instead of using DOMContentLoaded. The method onStateChange of your progress listener will always be called with STATE_STOP and STATE_IS_WINDOW flags when the page finishes loading - regardless of whether there is an error or not. You can call Components.
IsSuccessCode(aStatus) to see whether the page loaded successfully (note that this will only report network errors, HTTP errors like 404 will still count as success).
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.