This was completely unknown to me until a certain much-used Firebug feature was removed.
HTML preview feature available again in Firebug 1.8
They had pushed out a security update but removed the HTML preview feature which I use quite often due to my work with AJAX/JSON.
Fuck, what was I to do?
First, prevention is always better than a cure. Stop the automatic updates!
- Open up your addons manager (Firefox > Add-ons)
- In the top right, click on the cog icon
- Untick "Update Add-ons Automatically"
- For safe measures, also click on "Reset All Add-ons to Update Manually"
The second thing to do is Firebug specific. Go to the site and download 1.8beta4. It works fine so install it.