Selecting cell when invoke popup

Question

I have a table where the user can select the table cells with a mouse click, if they do a right click its brings up a PopupMenu but this doesnt effect what cells have been selected.
Ive looked at Microsoft Spreadsheet and if a right click is done over a cell that has been selected, all the cells selected remains but if it is clicked over a cell that is not selected then the cell that has just been clicked on becomes the current cell instead.
This seems a better way of doing it., so does anyone know how I can achieve this prefereably in a way that is both OS independent and input device independent.
Thanks Paul

Answer 1

Thanks
Ive posted my soln based on your info here. Its maybe more complicated then would uusually be required because my table allows row and column sorting.
protected void maybeShowPopup(MouseEvent e)
        /** Get selected cells
         *  have we clicked over area covered by selected cells
         *  if not we then reset to currently covered cell
        if (e.isPopupTrigger())
            try
                int row = table.rowAtPoint(e.getPoint());
                int col = table.columnAtPoint(e.getPoint());
                CellLocation cell
                    = new CellLocation( ( (TableSorter) table.getModel()).getRowAt(row),
                                       table.getColumnModel().getColumn(col).getModelIndex());
                ArrayList cells = ( (TableSorter) table.getModel()).getSelectedCells();
                if (!cells.contains(cell))
                     table.changeSelection(row, col, false, false);
            catch (Exception ex)
                ex.printStackTrace();
            popup.show(e.getComponent(), e.getX(), e.getY());
class CellLocation
     int row;
     int col;
     public CellLocation(int row, int col)
         this.row = row;
         this.col = col;
     public int getRow()
         return row;
     public int getCol()
         return col;
     public boolean equals(Object o)
         CellLocation otherCell = (CellLocation)o;
         if((otherCell.getRow()==this.getRow())&&
            (otherCell.getCol()==this.getCol())
             return true;
         return false;
Table Sorter methods ........
/** Returns the underlying model row index for a given table row index */
    public int getRowAt(int aRow)
        return  ((Integer) indexes.get(aRow)).intValue();
    /* The mapping only affects the contents of the data rows.
     * Pass all requests to these rows through the mapping array: "indexes".
    public Object getValueAt(int aRow, int aColumn)
        checkModel();
        return model.getValueAt( ( (Integer) indexes.get(aRow)).intValue(), aColumn);
    /** Retrieve a list of the selected cells */
    public ArrayList getSelectedCells()
        ArrayList selectedCells = new ArrayList();
        try
            int[] rows = table.getSelectedRows();
            for (int i = 0; i < rows.length; i++)
                int[] cols = table.getSelectedColumns();
                for (int j = 0; j < cols.length; j++)
                    selectedCells.add(new CellLocation( ( (Integer) indexes.get(rows)).intValue()
, table.getColumnModel().getColumn(cols[j]).getModelIndex()));
catch (Exception e)
e.printStackTrace();
return selectedCells;