[Key or key combination] SHIFT+TAB [Description] 
If the current cell is in edit mode, moves the focus to the previous cell in the current row. If the focus is already in the first cell of the row, commits any changes that were made and moves the focus to the last cell in the previous row. If the focus is in the first cell in the control, moves the focus to the previous control in the tab order of the parent container. If the current cell is not in edit mode, moves the focus to the previous control in the tab order of the parent container.