public Variables() {
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();

        WINDOW_HEIGHT = screenSize.height;
        WINDOW_WIDTH = screenSize.width;

        CANVAS_HEIGHT = WINDOW_HEIGHT * 4/5 ;
        CANVAS_WIDTH = WINDOW_WIDTH *4/5;
        
        THUMBNAIL_HEIGHT = WINDOW_HEIGHT * 1/5;
        THUMBNAIL_WIDTH = CANVAS_WIDTH * 1/5;
    }