I'm using latest IHG with latest FireFox 49.0.1 (add-on signing disabled).
The add-on works very well.
But I'm running into a strange bug.
So FireFox has a "restart" button.
It preserves your existing tabs, and loads them again when the browser starts up.
But when IHG is installed, it causes this weird glitch.
After restart, IHG causes the first tab with focus stays unloaded (the others, without focus, load fine).
It just sits there as a blank page.
It's definitely IHG causing it.
As soon as I disable the add-on, I don't have this problem.
Enable the add-on, and problem appears again.