Stuck trying to trigger the laser button in QtPlasmac with an external button

Been searching but I just can't sort this one out.

I just recently got my machine up and running and finally cutting (including THCAD-10 THC).  Searching on this forum has been a godsend!   I have a working Xbox 360 controller jogging the axis etc.  I've also done some basic HAL signal - pin connections to get my indicators, latching E-Stop etc. all working again with many thanks to the collective wisdom here.

But I'm stuck on one thing.  I'd like to hook one of the Xbox controller buttons up to the "Laser" button in QtPlasmac but cannot for the life of me figure that one out.   Ideally this would allow me to jog and mark the edge/origin with my xbox controller without having to go back to the mouse to click the laser/edge/origin button in the UI.

I found the qtplasmac.laser UI button in Halshow and I can monitor that and see it going active when I click it with my mouse.   I can link a signal in HAL to the Xbox button (input.0.btn-b) and monitor that also in Halshow.   But how do I link that signal (or input.0.btn-b directly) to trigger the the qtplasmac.laser UI button?  That UI button goes through 3 actions;  laser on, set edge, then set origin.   Is this why I'm unable to link it?  

Hoping this is something basic I just missed in all my digging and if so I apologize for having to ask.  :/

-Dave

Well, there is qtplasmac.ext_laser_touchoff (which of course, I just stumbled upon after posting my question)

The section "15.4. External HAL Pins" implies this is the "Laser" GUI function to set origin with/without rotation.  This turned out to be it.   I have answered my own question.  Leaving in forum in case someone else is hunting for the answer.