Hello mgaughan,
This is a normal behaviour – if you set the grid’s height to a certain value, it positions all needed elements (header, scrollbar, statusbar, toolbar, etc.) and whatever is left of the height is used for row display. In your case, you can just adjust the height property of the grid. Moreover, you can set scrollmode to “logical” and the grid will always display whole rows no matter what the scroll position is (use this together with the height adjustment).
Best Regards,
Dimitar
jQWidgets team
http://www.jqwidgets.com/