[Страдалецъ]

В общем примерно так:

Код:

procedure TForm1.RichEdit1KeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
var
  Coords: TPoint;
begin
 if (Shift = [ssCtrl]) and (Key = VK_SPACE)
 then begin
      RichEdit1.Perform(EM_POSFROMCHAR, WPARAM(@Coords), RichEdit1.SelStart);
      ListBox1.Left := RichEdit1.Left + Coords.X;
      ListBox1.Top := RichEdit1.Top + Coords.Y;
      ListBox1.Show;
      ListBox1.SetFocus
      end;
end;

procedure TForm1.ListBox1KeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
 case Key
 of VK_ESCAPE: ;
    VK_RETURN: RichEdit1.SelText := ListBox1.Items[ListBox1.ItemIndex];
    else Exit;
 end;
 ListBox1.Visible := False;
 RichEdit1.SetFocus;
end;.