This link (http://www.java.com/en/download/help/jcp_security.xml) describes the Java security settings for applets in the browser. For setting "high" it says":
This is the minimum recommended (and default) security level setting. Applications that are signed with a valid or expired certificate and include the Permissions attribute in the manifest for the main JAR file are allowed to run with security prompts. Applications are also allowed to run with security prompts when the revocation status of the certificate cannot be checked. All other applications are blocked.
We're trying to establish if the Permissions level of our applet has any impact here - it's not mentioned but it seems logical a sandbox-level applet could legitimately run with lower permissions. Can anyone categorically answer this?