/**
                         * @description
                         *
                         * CG.Screen is a child of CG.Director and a container to collect/group CG.Layers and/or CG.B2DWorld
                         *
                         ```
                        
                         var s = new CG.Screen({
                           name: 'menuscreen'
                         })
                        
                         ```
                         *
                         * @class CG.Screen
                         * @extends CG.Class
                         *
                         * @param {string} screenname the name of the screen
                         */
                        CG.Class.extend('Screen', {
                            /**
                             * Options:
                             * name {string}
                             *
                             * @constructor
                             * @method init
                             * @param options
                             * @return {*}
                             */
                            init: function (options) {
                                CG._extend(this, {
                                    /**
                                     * @property name
                                     * @type {string}
                                     */
                                    name: '',
                                    /**
                                     * @property position
                                     * @type {CG.Point}
                                     */
                                    position: new CG.Point(0, 0),
                                    /**
                                     * @property xscale
                                     * @type {Number}
                                     */
                                    xscale: 1,
                                    /**
                                     * @property yscale
                                     * @type {Number}
                                     */
                                    yscale: 1,
                                    /**
                                     * @property layers
                                     * @type {Array}
                                     */
                                    layers: []
                                })
                        
                                if (options) {
                                    CG._extend(this, options)
                                }
                        
                                return this
                            },
                            create: function () {
                        
                            },
                            /**
                             * @method update
                             */
                            update: function () {
                                for (var i = 0, l = this.layers.length; i < l; i++) {
                                    this.layers[i].update()
                                }
                            },
                            /**
                             * @method draw
                             */
                            draw: function () {
                                Game.b_ctx.save()
                                for (var i = 0, l = this.layers.length; i < l; i++) {
                                    if (this.xscale !== 1 || this.yscale !== 1) {
                                        Game.b_ctx.translate((Game.width - (Game.width * this.xscale)) / 2, (Game.height - (Game.height * this.yscale)) / 2)
                                        Game.b_ctx.scale(this.xscale, this.yscale)
                        
                                        this.layers[i].draw()
                        
                                    } else {
                                        // if layers have a fixed position the layer stays always on top left
                                        // this is usefull for tilemaps. they have its own mapoffset
                                        // TODO: may find a better solution
                                        Game.b_ctx.save()
                                        if (this.layers[i].fixedPosition) {
                                            Game.b_ctx.translate(0, 0)
                                        } else {
                                            Game.b_ctx.translate(this.position.x, this.position.y)
                                        }
                                        this.layers[i].draw()
                                        Game.b_ctx.restore()
                                    }
                                }
                        
                                Game.b_ctx.restore()
                            },
                        
                            /**
                             * @description add a CG.Layer object to the layer array
                             * @method addLayer
                             * @param {layer} layer to add
                             */
                            addLayer: function (layer) {
                                this.layers.push(layer)
                                return this
                            },
                        
                            /**
                             * @description find CG.Layer by name
                             * @method getLayerByName
                             * @param {string} layername find layer by name
                             * @return {boolean/layer}
                             */
                            getLayerByName: function (layername) {
                                for (var i = 0, l = this.layers.length; i < l; i++) {
                                    if (this.layers[i].name == layername) {
                                        return this.layers[i]
                                    }
                                }
                                return false
                            }
                        })