在画布上设置透明面板

I have a canvas and I want when mouse entered it, some transparent Jpanel containing some components displayed on top of my canvas. I used JlayeredPane for this; but as you see in following example when I want to display transparent panel on top of canvas, by adding it to jLayeredPane on upper layer, It's background is shown as color of the panel that is under canvas. I have a canvas and I want when mouse entered i