Comment 1 for bug 1200713

Kapil gave the example of bool. The GUI is actually doing it wrong, AFAICT, actually. Here's an except from our config.yaml:

  staging:
    description: |
      Connect the Juju GUI to the staging backend (i.e. a simulated Juju
      environment). Currently juju-core does not support the staging
      backend. For this reason, this option is ignored if the charm is
      deployed using juju-core.
    type: boolean
    default: false

The given default is actually a string, "false," and not the boolean value false. YAML specifies a typecast (http://www.yaml.org/spec/1.2/spec.html#id2803629):

  staging:
    description: |
      Connect the Juju GUI to the staging backend (i.e. a simulated Juju
      environment). Currently juju-core does not support the staging
      backend. For this reason, this option is ignored if the charm is
      deployed using juju-core.
    type: boolean
    default: !!bool false