I have tested this, but unfortunately I was not able to reproduce the described behavior. I simply added .NET Framework as a pre-install prerequisite and it was displayed in the foreground.
In order for me to further investigate this issue, could you please forward me a sample project which reproduces this issue, by e-mail at support at advancedinstaller dot com? Or maybe just a test-case which I can follow in order to reproduce this issue in a newly created project.
Looking forward to hearing from you.