Obtaining the "active" Desktop/Monitor under OSX?

[Paul Dupuis]

I remember when the multiple Desktop feature was introduced on OSX
(Yosemite I think?) there was a very active discussion on this email
list about how to tell what monitor (in a multiple monitor
configuration) your application was starting up on.

I have tried searching for this but my search keyword choices (or search
skills) are failing me.

Does anyone remember how to do this? Or can point me to the
answer/workaround from the discussion?

OR has anything been added to the LiveCode language in 8.x.x+ that lets
an app tell what monitor it is starting up on? I check the 8.1.4
Dictionary, but I could not find anything.

The 1st line of the screenrects is the "primary" monitor, which with the
OSX feature is not necessarily the monitor the app is launching on
running on (it has its menubar on)

Thank you in advance for any pointers/guidance.