public final void setSelected(DateCell cell) {
        setKeyboardSelectedCell(cell);

        DateCell last = selectedCell;
        selectedCell = cell;

        if (last != null) {
            last.onSelected(false);
        }
        if (selectedCell != null) {
            selectedCell.onSelected(true);
        }
    }
Highlighting, selectable cell grid. Used to help construct the default
calendar view.
stroom-core-client-widget/src/main/java/stroom/widget/datepicker/client/DateGrid.java