Doesn't work for me. I followed the instructions it gave me (see below), but I still can't get New Tab Tools to work. I was using Speed Dial Ad On before the Quantam update. Since that Ad On no longer works on the latest Firefox update, I thought I'd try New Tab Tool. Very disappointed that I can't get it to work. I'd appreciate some help in getting this to work or I will have to downgrade back to earlier version of Firefox so I can at least use Speed Dial again.

These are the instructions I followed. I have everything set to these guidelines, but I still can't get New Tab Tools to work:

New Tab Tools couldn't start properly. Try these:

If cookies are disabled, add an exception for moz-extension://dc076228-e574-4cbd-a300-a814c6ce7188/.
Go to about:config and check dom.indexedDB.enabled is set to true.

You will need to restart New Tab Tools (or just restart Firefox) for these changes to have an effect.
New Tab Tools cannot start if Firefox is set to "never remember history" or "always open in private browsing mode".