Listbox height: access question

First off, I am still very early in learning stages, and am in fact editing/modifying an existing set of scripts to add additional functionality. I have run into an issue with a listbox whereby I wish to be able to adjust it's height according to list.items count. However, it always ends up as a single row instead of the normal height by line count.

Here is an example of what I have attempted to do:

 
 
listbox lbx_scripts "" height:25 -- this works and I wish 25 to be max size, but would also like to
 
                                             -- adjust downwards if item count is less than 25
 
 
 
    for j = 1 to displaylist.count do
            (
            format "Displaylist.count = %\r\n" displaylist.count --just to show actual list count
            if displaylist.count <= 25 then lbx_scripts height: displaylist.count
            else lbx_scripts height: 25
             )

Of course the above fails with an error

-- Type error: Call needs function or class, got: ListBoxControl:lbx_scripts <<

I need to know how to access the "height:" property outside of the initial declaration. the listbox named lbx_scripts.height property is only in pixels which appears to be the only height I can adjust outside of that initial declaration line.

Is there anyway that I can access that property to adjust it programmatically?