This is not a bug. Simply buttons in "inner" sub-window are linked to each other, not to right corner. But yellow buttons are.
Is this an issue that do not allows you to use popup designer?
I wrote this up and passed it along.
Our internal bug # is HM-5111
You can email with a subject "Please notify me when bug # HM-5111 is resolved" or you can check the release forums to see when it is resolved for the release.