How to override the standard row selection behaviour of a TDBGrid

Problem/Question/Abstract:

How to override the standard row selection behaviour of a TDBGrid

Answer:

The standard behaviour is as follows:

Keyboard - If you hold down the Shift key and use the arrow keys the rows are continuously selected as you step through the grid. Clear all selections with the Escape key.

Mouse - If you hold down the Ctrl key and click with the mouse you can select/ deselect individual rows.

The following code allows selection/ deselection by hitting the spacebar and also allows stepping up/ down with the arrow keys without causing deselection.

procedure TForm1.DBGrid1KeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
  if (Shift = []) then
  begin
    case Key of
      VK_UP:
        begin
          Key := 0;
          TDBGrid(Sender).DataSource.DataSet.Prior;
        end;
      VK_Down:
        begin
          Key := 0;
          TDBGrid(Sender).DataSource.DataSet.Next;
        end;
      VK_Space:
        begin
          Key := 0;
          TDBGrid(Sender).SelectedRows.CurrentRowSelected :=
            not (TDBGrid(Sender).SelectedRows.CurrentRowSelected);
        end;
    end;
  end;
end;