I have set a contextmenu on the grid and am changing the state of various items in that menu in response to the selection changing on the grid.  All works as expected if i first left click on a row before right clicking on it (in that the context menu is correctly based on the currently selected row), however if i right click on an unselected row, selection doesn't change and as such i don't get a correct context menu.

How do i get the grid to change selection on right click ?