Revision 1199

(TableGrid.__init__): Create an
        instance variable to keep track of how many rows are selected.
        Subscribe once to the the events we are interested in.
(ThubanGrid.OnRangeSelect): Only handle event if event handling
        hasn't been turned off.
(ThubanGrid.OnSelectCell): Only handle event if event handling
        hasn't been turned off.
(ThubanGrid.ToggleEventListeners): Rather than subscribe None
        as an event listener (which changes the event handler stack)
        simply set an instance variable to False. This is checked in
        the event handlers.
(ThubanGrid.GetNumberSelected): Return the number of currently
        selected rows.
(TableFrame): Inherit from ThubanFrame so we can have a
        status bar and control buttons.
(QueryTableFrame.__init__): Create a status bar. Fixes RTbug #1942.
        Explicitly set which items are selected in the operator choice and
        action choice so there is always a valid selection. Fixes RTbug #1941.
        Subscribe to grid cell selection events so we can update the
        status bar.
(QueryTableFrame.UpdateStatusText): Update the status bar with
        how many rows are in the grid, how many columns, and how many
        rows are selected.
(QueryTableFrame.OnGridSelectRange, QueryTableFrame.OnGridSelectCell):
        Call UpdateStatusText when cells are (de)selected.
(QueryTableFrame.OnQuery): Use the string value in the value
        combo if either the selected item index is 0 or if the string
        cannot be found in the predefined list (this happens if the
        user changes the text). Fixes RTbug #1940.
        Only turn off the grid event listeners if there a query comes
        back with a none empty list of ids. in the case that the list
        is empty this causes a grid.ClearSelection() call to actually
        clear the grid selection which causes the selected items in
        the map to be deselected. Fixes RTbug #1939.