I wish to override behavior of FileDialog call of awt library so as to not invoke any native calls to open up file chooser. I am planning to achieve it by overriding FileDialog with a stub library and forcing it to load before standard ones whenever an applet is loaded using icedTea firefox java plugin.
For an intermittent fix, I have come up with a hack to replace standard JRE with custom one, wherein FileDialog's show method is overridden to a no-op. Then, the location of custom JRE is specified in ~/.icedtea/deployment.properties file using custom.jre property.(Please confirm property name for your version of icedtea plugin by referring source code.)