I put a flashlight inside a clear jar and close it up. I can still switch the flashlight off and on! If the jar isn't clear, then I can't. And I can't find a way to intercept a switch verb before it occurs so I can slip in a ContainsReachable function.
I tried digging in to the default code for 'turnon' command to fix it there but I can't find anything resembling a script, not sure if object.switching is done below the ASL level. Anyone?

This time you have to import the object type 'switchable'. There you can change the functions turnon and turnoff like this:

   <turnon type="script">
      found = false
	  foreach (obj, ScopeReachable()){
		if (obj = this){
			found = true
		}
	  }
	  if (found){
		  if (this.switchedon) {
			msg (DynamicTemplate("AlreadySwitchedOn", this))
		  }
		  else {
			if (HasString(this, "switchonmsg")) {
			  msg (this.switchonmsg)
			}
			else {
			  msg (DynamicTemplate("SwitchedOn", this))
			}
			this.switchedon = true
		  }
	  } else {
			msg(DynamicTemplate("DefaultTurnOn", this))
	  }	
    </turnon>
    <turnoff type="script">
	  found = false
	  foreach (obj, ScopeReachable()){
		if (obj = this){
			found = true
		}
	  }
	  if (found){
		  if (not this.switchedon) {
			msg (DynamicTemplate("AlreadySwitchedOff", this))
		  }
		  else {
			if (HasString(this, "switchoffmsg")) {
			  msg (this.switchoffmsg)
			}
			else {
			  msg (DynamicTemplate("SwitchedOff", this))
			}
			this.switchedon = false
		  }
	  } else {
			msg(DynamicTemplate("DefaultTurnOff", this))
	  }	
    </turnoff>

Could you test this code and tell me if it is working? Thanx

Thanks Pertex. Can you clarify the steps for me? I can't figure out what you mean. Import as in edit an aslx file directly? Which one? Or do you mean expose the switchable object type in the editor and modify that? I did the later, can't find anything referring to turnon or turnoff functions. I tried the former, sort of, but I can't figure out where.
Thanks again, nice to know it's not locked up in C# or something

edit: of course, right after my post I figured it out. That line this.lightstrength = "strong" in the original script was the key, guess I didn't look far enough! (haven't explored the object-type list much except to mess with default object stuff.

You can just import it in the editor:

First click on Filter and then Show Library Elements

Expand the object tree to find:
Advanced>Object Types>Switchable

Copy switchable and in the attributes list are two separate attributes, one for turnon and another for turnoff.

Copy and past all the code between <turnon type="script"> and </turnon> into the turnon attribute (overwriting what's there) and then the same with turnoff.

thank you Liam and Pertex. The suggested script works. But even better, I'm now aware of another layer to investigate for questions such as these.