An AWT application does not show the Unicode character \u0159, but the Swing application does.

Attachments of this report:
testcases.zip - testcases for both AWT and Swing (both sourcecode and bytecode)
screenshots.zip - screenshots of the tests under Windows XP SP 2
Czech.png - screenshot of the customer's real live application

Run the testcase by entering
java -cp . CzechFrame
respectively
java -cp . CzechJFrame

These are the results

AWT (CzechFrame)
----------------
                   JDK 1.6 JDK 1.5.0_10 JDK 1.4.2_13
Solaris 9 OK FAILED FAILED
Windows XP SP 2 FAILED FAILED FAILED


Swing (CzechJFrame)
-------------------
                   JDK 1.6 JDK 1.5.0_10 JDK 1.4.2_13
Solaris 9 OK OK OK
Windows XP SP 2 OK OK OK


FAILED means that a rectangle is shown rather than the expected character.
I've just found one more regularity:

Running Java Application from Intellij IDEA (I used 10.0.3 Community Edition) resolves this issue (in both Run & Debug modes).
Running the same application other ways (including Debug under MS Visual C++ 2010 Express) shows squares.
Tested on Windows 7.

PS: WIN32 API function 'CreateFont' is called with fdwCharSet=DEFAULT_CHARSET in all cases. Seems like this value is not stable in its result.