Incompatibility when built in 1.4 and run in 1.3...any ideas???

Question

We used to use the class FocusManager earlier in the code given below. It works fine when compiled and run in JDK 1.3.
When this code is compiled in 1.4 and the client runs it in 1.3 -> it throws a NoClassDefFoundError i.e. java/awt/DefaultKeyboardFocusManager
I understand the FocusManager changed in 1.4 but without backward compatibility where we are using only the abstract base class FocusManager??? Anybody faced this kind of issue. Have any ideas or workaround???
Thanks in Advance
addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent evt) {
editor.repaint();
if (evt.getKeyCode() == KeyEvent.VK_TAB) {
evt.consume();
FocusManager f = FocusManager.getCurrentManager();
if (f != null) {
if (evt.isShiftDown())
f.focusPreviousComponent(editor);
else
f.focusNextComponent(editor);
EXCEPTION -->
Exception in thread "main" java.lang.NoClassDefFoundError: java/awt/DefaultKeyboardFocusManager
at COM.inovie.teamCenter.gui.FixedHeightText.<init>(FixedHeightText.java:36)
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Answer 1

True. I know... we used only FocusManager which is
present in 1.3. That is why the question. Since there
is no reference to DefaultKeyboardFocusManager in the
code, it should run the same way when we compile it in
1.3 or 1.4 Yes, there is. If you look at FocusManager in 1.4, it extends DefaultKeyboardFocusManager which didn't exist in 1.3. So, it's apparently only there for backward compatibility. If you COMPILE it using 1.3, then it may work in both 1.3 and 1.4, but if you compile it using 1.4, I'd say your out of luck.