Document on* handlers (for extension authors' sake)

var optionsChangedCallbacks = [];

var uiCurrentTab = null;

/**

 * Register callback to be called at each UI update.

 * The callback receives an array of MutationRecords as an argument.

 */

function onUiUpdate(callback) {

    uiUpdateCallbacks.push(callback);

}

/**

 * Register callback to be called when the UI is loaded.

 * The callback receives no arguments.

 */

function onUiLoaded(callback) {

    uiLoadedCallbacks.push(callback);

}

/**

 * Register callback to be called when the UI tab is changed.

 * The callback receives no arguments.

 */

function onUiTabChange(callback) {

    uiTabChangeCallbacks.push(callback);

}

/**

 * Register callback to be called when the options are changed.

 * The callback receives no arguments.

 * @param callback

 */

function onOptionsChanged(callback) {

    optionsChangedCallbacks.push(callback);

}