WebListBox.ScrollTo
From Xojo Documentation
Method
Scrolls the ListBox to the specified RowIndex position.
Notes
If RowIndex is greater than the last row in the ListBox (WebListBox.RowCount-1), an OutOfBoundsException is raised.
Example
The following scrolls to the last row of the ListBox:
ListBox1.ScrollTo(ListBox1.RowCount - 1)