Extra window is created on taskbar , when splash screen image is set to a new image using setImageURL(url); This happens only on jdk7.0 ( dolphin) build 04 . A similar bug was got fixed in mustang b91, bug id 6427311 ( regression: An Extra window is created on the taskbar , when splash screen is on the screen ).
This work fine in mustang b104 ( which i have) even it works fine in dolphin b01 , b02 & b03. Hence it is a regression.

Step to Reproduce
-------------------
1) Run the attached program.
 java -splash:animdog.gif GetSetImageUrlTest
wait for animated image changes to java cup image, you can see an extra window is created on the taskbar with the title as "java". Once again the java cup image is changed back to animated dog image, you can see the extra window on the taskbar. If you see the same then the bug is reproduce.