Code:

procedure TForm1.FormCreate(Sender: TObject);

begin

DBLookupCombo1.Visible := False;

DBComboBox1.Visible := False;

end;

procedure TForm1.DBGrid1DrawDataCell(Sender: TObject; const Rect: TRect;

Field: TField; State: TGridDrawState);

begin

if (gdFocused in State) then

begin

   if (Field.FieldName = DBLookupCombo1.DataField) then

   begin

     DBLookupCombo1.Left := Rect.Left + DBGrid1.Left;

     DBLookupCombo1.Top := Rect.Top + DBGrid1.top;

     DBLookupCombo1.Width := Rect.Right - Rect.Left;

     DBLookupCombo1.Visible := True;

   end

   else if (Field.FieldName = DBComboBox1.DataField) then

   begin

     DBComboBox1.Left := Rect.Left + DBGrid1.Left;

     DBComboBox1.Top := Rect.Top + DBGrid1.top;

     DBComboBox1.Width := Rect.Right - Rect.Left;

     DBComboBox1.Visible := True;

   end

end;

end;

procedure TForm1.DBGrid1ColExit(Sender: TObject);

begin

if DBGrid1.SelectedField.FieldName = DBLookupCombo1.DataField then

   DBLookupCombo1.Visible := false

else if DBGrid1.SelectedField.FieldName = DBComboBox1.DataField then

   DBComboBox1.Visible := false;

end;

procedure TForm1.DBGrid1KeyPress(Sender: TObject; var Key: Char);

begin

if (key <> chr(9)) then

begin

   if (DBGrid1.SelectedField.FieldName = DBLookupCombo1.DataField) then

   begin

     DBLookupCombo1.SetFocus;

     SendMessage(DBLookupCombo1.Handle, WM_Char, word(Key), 0);

   end

   else if (DBGrid1.SelectedField.FieldName = DBComboBox1.DataField) then

   begin

     DBComboBox1.SetFocus;

     SendMessage(DBComboBox1.Handle, WM_Char, word(Key), 0);

   end;

end;

end;