openjdk7 is no valid platform in netbeans 8.0

[Dr. A. Haakh]

Hi,

In netbeans you can choose the java platform to use for a given project.

Netbeans-8.0 works fine with openjdk6 and openjdk8 but gives an
error-dialog when I try to add openjdk7.
It says:
"Cannot detect and install the selected platform. The java or javac may not be executable."
But java and javac in jdk and java in jre work fine...

Maybe this is due to the missing javafx-support??

Any hints??
Andreas