Tie State to, was added to make two datagrids on the same screen, scroll to the same place. It is used in the Media File List.
And NO. DO NOT implement toggle behaviour in this manner! Toggles must either be handled by setting object state (look at some of the other orbiter commands, I can't think of them off the top of my head) in the onActivate and onLoad/onUnload sections...or by implementing custom code in src/Orbiter/ScreenHandler.cpp (look at the wiki page for Integrating custom controls into Orbiter.)