Hi! Just a heads up that folks from the dev tools team will be monitoring this thread and are on-hand to answer questions. We'll try not to thread sit too much. :) In brief, the Developer Edition is a new release channel for Firefox, replacing Aurora (our pre-Beta channel). Everything else about the release cadence is the same. There are four major new features here: 1. The Firefox Tools Adapter ("Valence"), which le…
1. HTTP Request builder (think cURL with a nicer GUI and the ability to save presets);
2. Web Proxy, able to "stop-and-modify" requests (think Fiddler or Charles);
3. Network conditions simulator for throttling, packet dropping and limited bandwidth, with profiles (e.g. GPRS);
4. Local Mock REST API, with a few predefined endpoints (e.g. /users/) + the ability to create new ones (with configurable values such as random integers between X and Y or a random string which is a valid e-mail);
5. Multi-touch simulator (with a modifier key);
6. A usability test facilitator, able to create test scripts and automatically record timing and extra information (e.g. define a task that ends when user clicks the element with id X; when said user clicks #X, you annotate the time, the number of misclicks, etc). You could also implement this for static images, with clickable regions. I would love you for this one.