Comment 37 for bug 122529

That is not a bug but rather a setting that needed to be changed.
It doesnt have a good change of changing that from setting to default. You can either file/look for bug upstream at: https://bugzilla.mozilla.org/
I will leave this as incomplete until you have decided on what you would like to do but this isn't a Ubuntu change rather a Mozilla change. If you file or find a bug upstream please post the link here and we will decide if that is the exact issue as there may be 100 bugs close to your bug but not the same.