Hi, it seems shotguns java applet does not refer to its codebase. This causes security warning popups for users everytime they press a menu or button. Can you please re-sign your applet with the proper codebase?
See this document for reason and requirement for the codebase property:
http://docs.oracle.com/javase/7/docs/technotes/guides/jweb/security/no_redeploy.html