third_party/js/mozmill/shared-modules/prefs.js
function preferences_setPref(prefName, value, interfaceType) {
    try {
      switch (typeof value) {
        case ('boolean'):
          this.prefBranch.setBoolPref(prefName, value);
          break;
        case ('string'):
          this.prefBranch.setCharPref(prefName, value);
          break;
        case ('number'):
          this.prefBranch.setIntPref(prefName, value);
          break;
        default:
          this.prefBranch.setComplexValue(prefName, interfaceType, value);
      }
    } catch(e) {
      return false;
    }

    return true;
  }
function preferences_setPref(prefName, value, interfaceType) {
    try {
      switch (typeof value) {
        case ('boolean'):
          this.prefBranch.setBoolPref(prefName, value);
          break;
        case ('string'):
          this.prefBranch.setCharPref(prefName, value);
          break;
        case ('number'):
          this.prefBranch.setIntPref(prefName, value);
          break;
        default:
          this.prefBranch.setComplexValue(prefName, interfaceType, value);
      }
    } catch(e) {
      return false;
    }

    return true;
  }
function preferences_setPref ( prefName , value , interfaceType ) { try { switch ( typeof value ) { case ( 'boolean' ) : this . prefBranch . setBoolPref ( prefName , value ) ; break ; case ( 'string' ) : this . prefBranch . setCharPref ( prefName , value ) ; break ; case ( 'number' ) : this . prefBranch . setIntPref ( prefName , value ) ; break ; default : this . prefBranch . setComplexValue ( prefName , interfaceType , value ) ; } } catch ( e ) { return false ; } return true ; }
Set the value of an individual preference.

@param {string} prefName
The preference to set the value of.
@param {boolean/number/string/complex} value
The value to set the preference to.
@param {string} interfaceType
Interface to use for the complex value
(nsILocalFile, nsISupportsString, nsIPrefLocalizedString)

@return Returns if the value was successfully set.
@type boolean
Set the value of an individual preference .