Your example, setting a data table into a Data Grid Box(), appears much closer to what a data table looks like.
names default to here(1);
dt=
// Open Data Table: big class.jmp
// → Data Table( "big class" )
Open( "$SAMPLE_DATA/big class.jmp" );
nw = New Window( "Example", ,x=data grid box() );
dtx = x << set data table(dt);
However, JMP has actually created a Data Browser Box. Viewing the Tree Structure of display window shows the makeup of the Display Object. The easiest way to access this, is to right click on any of the grey triangles in front of the Outline Boxes in the display and selecting
Edit=>Show Tree Structure
The issue with your example code, is that it does not contain any Outline Boxes. Therefore, I just modified your code and added in a a simple Outline Box().
names default to here(1);
dt=
// Open Data Table: big class.jmp
// → Data Table( "big class" )
Open( "$SAMPLE_DATA/big class.jmp" );
nw = New Window( "Example", ob=outlinebox("test",x=data grid box() ));
dtx = x << set data table(dt);
From the Display Tree output, one can see the Data Browser Box
To see what messages are available to manipulate a Data Browser Box, one needs to go to the Scripting Index.
While there are a few messages that are similar to what can be done with a Data Table, there are no messages that control the scrolling of the window.
Jim