Be careful with old versions!
These versions are displayed for reference and testing purposes. You should always use the latest version of an add-on.
Thanks to Cody Richmond for the amazing refactoring and help!
1) works on all recent Firefox versions
2) much improved hiding algorithm (html5 tags etc.)
3) for anyone suggesting an easy way to show everything again: it's not possible, the only (simple 1 click way) is to reload the page :)