I have read this discussion track multiple times to make sure the initial impression I got is valid. That impression is that a lot of guessing as to what an object or function can do, and what the syntax might be if it may be able to do what is desired.
The current implementation of JSL is not consistant from object to object. That is, how one works with a button box object, syntactically, and capability is not the same as one works with a list box object, etc. However, all of the capabilities, and the syntax to use is detailed for each funjction, object and display box is detailed in the Scripting Index.
Help==>Scripting Index
The question in this discussion track on if, and how a combo box can change is answered in the Scripting Index
If a capability isn't listed, the function/object/display box doesn't have that ability. And if it does, the example will show you the syntax.
I recognized the confusion expressed in this discussion track, because it is where I used to live. And the solution I found has been the Scripting Index. I am too old to be able to keep all of the differences in the functions/objects/display boxes sorted out in my head.
Jim