public show( visible : boolean ) {
    if ( visible ) {
        this.background = new Sprite( PIXI.Texture.fromCanvas( document.getElementById( 'gameCanvas' ) as HTMLCanvasElement ) );
        let leftTop : PIXI.Point = this.viewport.getAlignedPoint( ViewportAlign.LEFT_TOP );
        this.background.position.set( leftTop.x, leftTop.y );
        this.background.scale.set( Viewport.BACKGROUND_WIDTH_LANDSCAPE / this.background.width, Viewport.GAME_HEIGHT_LANDSCAPE / this.background.height );

        let blurFilter = new PIXI.filters.BlurFilter( 4, 2 );
        blurFilter.padding = 100;
        blurFilter.autoFit = false;

        let darkenFilter = new PIXI.filters.ColorMatrixFilter();
        darkenFilter.brightness(0.2);
        darkenFilter.padding = 100;
        darkenFilter.autoFit = false;

        this.background.filters = [
            blurFilter,
            darkenFilter
        ];

        this.addChildAt( this.background, 0 );
    }
    this.visible = visible;
}