The Scrolled List widget is a scrolled window which contains a list widget. Thus a Scrolled List is not a widget but a compound object consisting of a List widget and a Scrolled Window: the Scrolled Window provides a viewpoint into the List widget.
The Visible Item Count resource controls the size of the Scrolled Window viewpoint into the List widget.
For more information, consult XmCreateScrolledList(3X) in the OSF/Motif Programmer's Reference.
NOTES
The Scrolled List has some internal default callbacks associated with the Scroll Bars - you are advised to leave the scrolling behavior well alone.
See also: