As per the screenshot the number of tabs are fixed, so you can have
another tab - order selector - where you can configure the order. Btw, I
would prefer this to be done as a container and subcomponent structure
instead of a blobbed up dialog.
I tested in 126.96.36.199 and it is working fine. Can you test with latest
service pack? The issue seems to be specific to your instance. Do you
see ny errors in browser console or network tab when you load the page?
Also, check the error logs. There might be some error or warning
statement issue related to the conversion of CF.
IF you have already migrated to 6.4, you should use sling model
exporter and export the content as json