Fix bug 2142296 where the user couldn't back out of the JetBoy demo.

The application was trapping the key up event on the back key. It
worked on Donut because the framework implemented the "back" behavior
on the key down. The fix consists in sending the key up event on the
back button to the Activity class.

samples/JetBoy/src/com/example/android/jetboy/JetBoy.java

@@ -133,19 +133,22 @@ public class JetBoy extends Activity implements View.OnClickListener {
      */
     @Override
     public boolean onKeyDown(int keyCode, KeyEvent msg) {
-
-        if (keyCode == 4)
-            super.onKeyDown(keyCode, msg);
-
-        return mJetBoyThread.doKeyDown(keyCode, msg);
+        if (keyCode == KeyEvent.KEYCODE_BACK) {
+            return super.onKeyDown(keyCode, msg);
+        } else {
+            return mJetBoyThread.doKeyDown(keyCode, msg);
+        }
     }
 
     /**
-     * Standard override for key-up. We actually care about these, so we can
-     * turn off the engine or stop rotating.
+     * Standard override for key-up.
      */
     @Override
     public boolean onKeyUp(int keyCode, KeyEvent msg) {
-        return mJetBoyThread.doKeyUp(keyCode, msg);
+        if (keyCode == KeyEvent.KEYCODE_BACK) {
+            return super.onKeyUp(keyCode, msg);
+        } else {
+            return mJetBoyThread.doKeyUp(keyCode, msg);
+        }
     }
 }