Checkboxes on  panels behave eratically the one that is clicked first opens when even the other is clicked .The exact steps for reproduction are :

1. Install Build 81 on Linux 7.1 . Start Java2Demo normally (using <JDK_B81_HOME>/bin/java -jar Java2Demo.jar in the directory <JDK_B81_HOME>/bin/java 
2. Click Arcs_Curves Tab or images Tab ( Or practically almost any tab )
3. You see four panels (i'll call them Top(T) , Bottom(B) , Left (L) ,
Right (R) ) Drop down (DD)
4. Click the  DD of the TL click it back to close .
5. Click the  DD of the TR click it back to close .
6. Click the  DD of the BL click it back to close .
7. Should be ok till here .
8. Click the  DD of the BR the , DD of the BL Opens instead of the BR
panel .
9 . This reproducible on almost all tabs and is also reproducible on b81
.
10. More so sometimes its really weird 'coz sometimes if you click the
DD of the right control panel of the Java2Demo before any of the DDs of
the BR or BL panels .. and then click the DD of the BR panel the DD open
right in the center of the Demo.

Build used : Build 81 
OS -Linux 7.1
Hardware -Pentium 4