Why does Netscape Navigator or Internet Explorer throw a security exception when I use JSAPI in an applet?
JSAPI implementations require access to the AWT EventQueue. The built-in Java platform support in the browsers we’ve worked with denies an applet access to the AWT EventQueue. As a result, JSAPI implementations will be denied access to the AWT EventQueue. In addition, we are not aware of a way to configure the built-in Java platform support in these environments to allow access to the AWT EventQueue. The Java Plug-in (see http://java.sun.com/products/plugin), however, can be configured to allow an applet the necessary permissions it needs to use an implementation of JSAPI. As a result, we currently recommend using the Java Plug-in for applets that use JSAPI.