How do I access an array in o.expr.codebox?

MaxMSPbeginner
Chayan Tronson's icon

Chayan Tronson

Hi I'm new here and can't find syntax info anywhere for o.expr.codebox
I'm trying to access an array from cnmat.o.io.mouse, the screenDim array.
It looks like this: [screenwidth, screenheight]

I want to do something like:

/maxWidth = /screenDim[[0]]

AKA create a variable that just accesses this array for me.
I get error messages. Specifically that screenDim is unbound (what?) Any help would be appreciated. If there's some documentation somewhere a link would be nice too. Thanks.