A DESCRIPTION OF THE REGRESSION :
java version "1.6.0-beta2"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-beta2-b74)
Java HotSpot(TM) Client VM (build 1.6.0-beta2-b74, mixed mode, sharing)
OS:Windows XP Professional SP1+

JDK Demo "Metalworks",
1.File Menu->New
2.Input by other languages other than english(Chinese,Japanese) in the [Subj:] field.
The input window will contain a JInternalframe with the same title as the input window, i can maximize the input window by click the maximum button of the JInternalframe....


REPRODUCIBLE TESTCASE OR STEPS TO REPRODUCE:
C:\Program Files\Java\jdk1.6.0\demo\jfc\Metalworks\Metalworks.jar

RELEASE LAST WORKED:
5.0 Update 6

RELEASE TEST FAILS:
mustang-beta

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Just the same look as inputting in a normal window.
ACTUAL -
2 Frames,quite funny.
This changed occured in 1.6 b11. Prior to that, I did not see any composer window.