draw rect problem?

public void paint(Graphics g) {
if (!buffered){
buffer = createImage(50, 50);
bufferG=buffer.getGraphics();

buffered=true;
}
bufferG.setColor(Color.RED);

bufferG.drawRect(0, 0, (int) imageSize.getWidth(),
(int) imageSize.getHeight());
g.drawImage(buffer,100,100,this);
}

in this Applet file ,i set the background colour is "black" in void init()
,then i set some images one the surface,and last i use double buffer draw a rect image,but when i draw the image,the rect become ,a black solid rect ,how to make it become tranparent?

You should be using the Graphics2D class and the AlphaComposite class. See this Tutorial

Don't post the same question to more than one forum -- it just wastes people's time and makes them less likely to help you. I'm closing this and leaving the one in the correct forum -- the Swing/AWT copy -- open. I've taken the liberty of deleting the other copies for you.