Ghost/core/client/app/mixins/settings-menu-controller.js

import Ember from 'ember';

export default Ember.Mixin.create({
    application: Ember.inject.controller(),

    isViewingSubview: Ember.computed('application.showSettingsMenu', {
        get: function () {
            return false;
        },
        set: function (key, value) {
            // Not viewing a subview if we can't even see the PSM
            if (!this.get('application.showSettingsMenu')) {
                return false;
            }
            return value;
        }
    }),

    actions: {
        showSubview: function () {
            this.set('isViewingSubview', true);
        },

        closeSubview: function () {
            this.set('isViewingSubview', false);
        }
    }
});