Hi, Please refer to the following forum for more detail about the problem and my suggestion:
http://www.telerik.com/forums/grid-row-navigation-by-keyboard#ncKqVMBBqUe5ZymNXwpFgg

Summary: I think in Grid widget, there should be difference between selectable="cell" and selectable="row" (for keyboard Up&Down Arrow navigation). or perhaps you want to add another choice, example selectable: "row cell" (to replace the current setting for "row") and the selectable = "row", just select the row not cell and also DO NOT go to grid header!
I believe it's good that you enhance/solve this shortcoming inside the Grid design, because developer like us who has already decided row selection (selectable: "row") during design-time, it doesn't make sense that still the keyboard navigation is at the cell level, isn't it?

Thank you.