AWT Background Problem

When I first bring up the web page, I get the wrong background color (it's actually the foreground color - black - instead, although that might be coincidence). Refreshing the page makes the background of the applet area the same color as the HTML page background. Then, when I go to another tab and return, the background of the applet area is whatever was in that area on the page of the last tab that I visited. I actually wouldn't mind if the background in the applet area was transparent right to the background of the HTML page, but only the HTML page in which is resides - not wherever I was before ...

The problem occurred using Firefox, but was not repeatable in Opera. So, I'm guessing it's a Firefox bug. Anyone concur ? Disagree?

> Anyone concur ? Disagree?

to concur/disagree you would need to post the 'exact' code/steps that reproduces the problem.

lines in the code like this

.....

do not help

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;

/* 
 * This is like the FontDemo applet in volume 1, except that it 
 * uses the Java 2D APIs to define and render the graphics and text.
 */

public class Rooms extends JApplet {

final static Color bg = Color.white;
    final static Color fg = Color.black;
    final static Color red = Color.red;
    final static Color white = Color.white;

final static BasicStroke stroke = new BasicStroke(2.0f);
    final static BasicStroke wideStroke = new BasicStroke(8.0f);

Dimension totalSize;

public void init() {
        //Initialize drawing colors
        setBackground(bg);
        setForeground(fg);
    }

public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        Dimension d = getSize();
        int gridWidth = d.width / 6;
        int gridHeight = d.height / 2;

Color fg3D = Color.lightGray;

g2.setPaint(fg3D);
        g2.draw3DRect(0, 0, d.width - 1, d.height - 1, true);
        g2.draw3DRect(3, 3, d.width - 7, d.height - 7, false);
        g2.setPaint(fg);

int x = 5;
        int y = 7;
        int rectWidth = gridWidth - 2*x;
        int rectHeight = gridHeight - y - 5;

// draw Line2D.Double
        g2.draw(new Line2D.Double(x, y+rectHeight-1, x + rectWidth, y));
        x += gridWidth;

// draw Rectangle2D.Double
        g2.setStroke(stroke);
        g2.draw(new Rectangle2D.Double(x, y, rectWidth, rectHeight));
        x += gridWidth;

// draw Arc2D.Double       
        g2.setStroke(wideStroke);
        g2.draw(new Arc2D.Double(x, y, rectWidth, rectHeight, 90, 
                                 135, Arc2D.OPEN));
        x += gridWidth;

// NEW ROW
        x = 5;
        y += gridHeight;

// fill Ellipse2D.Double
        GradientPaint redtowhite = new GradientPaint(x,y,red,x+rectWidth, y,white);
        g2.setPaint(redtowhite);
        g2.fill (new Ellipse2D.Double(x, y, rectWidth, rectHeight));
        g2.setPaint(fg);
        x += gridWidth;

}

public static void main(String s[]) {
        JFrame f = new JFrame("Rooms");
        f.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {System.exit(0);}
        });
        JApplet applet = new Rooms();
        f.getContentPane().add("Center", applet);
        applet.init();
        f.pack();
        f.setSize(new Dimension(550,100));
        f.setVisible(true);
    }

}

1) You extend JApplet. In such scenarios (where you use Swing components) it is recommended to override paintComponent() for custom painting
2) In the init() you are invoking setBack/Foreground(). Later on you are also calling g2.fill. What exactly are you trying to do here?
3) Your class has a main method? Who is supposed to be invoking that?
4) Your main method creates a JFrame and you add an applet instance to it? What exactly are you trying to do here?

Recommended reading: http://java.sun.com/docs/books/tutorial/uiswing/components/applet.html

running the code, I see the same problem in Firefox,
which seems to be resolved by adding the indicated line

Great! Thanks! ...... Now, why doesn't it work in Opera? (No change in config, etc.)

That last error is not UI related anymore but is specific to applets. Since the UI problem is solved I'll move this thread to our Applets forum.