On certain occasions, Firefox might choose not to display certain Java applets.
This is due to the applet having mixed security. In order to fix this, go to about:config and look for the name:
Change the value to false, and refresh the page containing the Java applet.
Continued discussion of undocumented Delphi 8 Property Access Specifiers, and other ways of adding and removing delegates / events handlers, including clearing the list of all the delegates / event handlers.