Original link:
http://www.cnblogs.com/lthxk-yl/p/3957276.html
Upon initialization, add:
ultraGrid1.DisplayLayout.Override.CellClickAction = Infragistics.Win.UltraWinGrid.CellClickAction.RowSelect;
Reproduced in: https: //www.cnblogs.com/lthxk-yl/p/3957276.html