initial_focus flag not working when an applet is compiled with 1.4 and run with 1.5

When a user runs an applet having any component(a button or textField), a loss
of focus happens after minimizing and maximizing the applet using TASKBAR BUTTON for applet.

This issue only reproducing when we are compiling the java file using 1.4 JDK
and running the class using JDK 1.5_xx and 1.6.

Step To Reproduce:
1. Run the test case listed in the comments after compiling it in JDK 1.4
2. Click on "FOcus Test" button to have intial focus on it.
3. Using taskbar button for applet window, minimize it and then maximize it.
4. Sometime you will see the intial focus is lost at the first clicks and
sometimes after repeating step 3 twice or thrice, you would see the issue.
 
If we compile the same class in JDK 1.5, it wont reproduce.
 
This behaviour can be seen using textfield item also.