shell_register_dde(+Type,
+Action, +Service, +Topic, +Command, +IfNotRunning)Associate DDE actions to a type. Type is the same type as
used for the 2nd argument of shell_register_file_type/4, Action
is the action to perform, Service and Topic
specify the DDE topic to address, and Command is the command
to execute on this topic. Finally, IfNotRunning defines the
command to execute if the required DDE server is not present.