On Windows, the manifest.webapp file for Firefox OS has an invalid path. The file must be edited manually to get the app to work.
- Install Cordova 3.5.0
- Create a new project: cordova create test
- In the test folder, add FxOS: cordova platform add firefoxos
- Package the app. For FxOS all that needs to be done is prepare: cordova prepare firefoxos
- In Firefox (at least version 26), go to about:app-manager
- Click Apps on the left, and then "Add Packaged App" on the bottom. Select test/platforms/firefoxos/www
- On the right-hand side, notice the error: "Launch path has to be an absolute path starting with '/': '\index.html'"
I have a fix ready for this and will submit a pull request on GitHub.