This issue is more of user experience in awkward situation that FX SDK 1.1.1 installer can't detect the JDK 6u13 just being installed as part of the cobundle.
After completing JDK 6u13 installation, FX SDK setup indicates the default (checked box) that requiring:
Name/ Version/ Action:
JDK 6u12+/ Required: 1.6.0 or higher. Found: nothing. / Download

and default recommended Download Folder is :
<System Drive>\Users\<user_home>\AppData\LocalLow\Sun\Java\jdk1.6.0_13

which is exactly JDK 6u13 is just installed as part of cobundle installation.

Absolutely, users can uncheck the default option and skip, but it users shouldn't have seen this download the JDK prerequisites at all


*** Test Bundle: Cobundle [Java SE SDK 6u13 & JavaFX SDK 1.1.1]
http://jre.sfbay.sun.com/java/re/jdk/6u13/promoted/plus/b91/bundles/windows-i586/jdk-6u13-javafx-1_1_1-windows-i586.exe

*** Test OS: x86 Vista Ultimate(sp1), x64 Vista (sp1)
     
Steps to reproduce:
------------------

1) Install the JDK 6u13/FX SDK 1.1.1 cobundle from
http://jre.sfbay.sun.com/java/re/jdk/6u13/promoted/plus/b91/bundles/windows-i586/jdk-6u13-javafx-1_1_1-windows-i586.exe
                     (/java/re/jdk/6u13/promoted/plus/b91/bundles/windows-i586/jdk-6u13-javafx-1_1_1-windows-i586.exe)

2) Proceed with the installation of JDK 6u13

3) When getting to the FX SDK installation part, ignore the black windows and just click 'Next' button, you will see the behavior displayed above

See attached screenshot for details.