public HandlerRegistration addRowHoverHandler(RowHoverEvent.Handler handler) {
        return addHandler(handler, RowHoverEvent.getType());
    }
Add a handler to handle {@link RowHoverEvent}s.

@param handler the {@link RowHoverEvent.Handler} to add
@return a {@link HandlerRegistration} to remove the handler
stroom-core-client-widget/src/main/java/com/google/gwt/user/cellview/client/AbstractCellTable.java