Issue found on mac 10.7.3 with jre 7u6 b16, to reproduce, input below command:
javaws http://jfx.us.oracle.com/hudson/view/Presidio/job/presidio/282/label=windows-i586-14/artifact/artifacts/deployed/LoginPreloader/LoginApp.jnlp
The login window can not capture any input into username and password text field from keyboard. Click on login directly can bring up the sample app.
Same issue with another sample:
javaws http://jfx.us.oracle.com/hudson/view/Presidio/job/presidio/282/label=windows-i586-14/artifact/artifacts/deployed/SignedAppAndPreloader/AllSignedApp.jnlp