FULL PRODUCT VERSION :
java version "1.7.0_04"
Java(TM) SE Runtime Environment (build 1.7.0_04-b20)
Java HotSpot(TM) 64-Bit Server VM (build 23.0-b21, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux 3.0.0-12-generic #20-Ubuntu SMP Fri Oct 7 14:56:25 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux


A DESCRIPTION OF THE PROBLEM :
This problem affects both Firefox and Chrome on Linux. If more than one tab is open, and there is an applet running in each tab that contains a text input field of any type, all applets become unusable, do not repaint properly, etc. I've narrowed it down to text components that cause the problem. JTextField, JTextArea, and JTextPane are all affected.

The problem does not occur if the applets are opened in separate windows and use the separate_jvm=true parameter. However, even with separate_jvm=true, the problem still occurs if the applets are opened under different tabs in the same browser window.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Create a simple applet that extends JApplet and adds a JTextArea

2. Open the applet in one browser tab (using either Firefox or Chrome). Note that it works as expected.

3. Open a new browser tab and open another copy of the applet. (or a different applet with a text input component). Both applets become unusable.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Both applets should work correctly with text fields
ACTUAL -
Both applets stop working, do not repaint, etc.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import javax.swing.JApplet;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;

public class MyApplet extends JApplet {
    public void init() {
try {
SwingUtilities.invokeAndWait(new Runnable() {
public void run() {
testGUI();
}
});
} catch (Exception ex) {
System.err.println("Error while initializing application.");
}
    }

    private void testGUI() {
add(new JTextArea());
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
None known. But problem does not occur if applets are opened in separate windows instead of separate tabs.