procedure TForm1.ImageEnView1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
  if (Winapi.Windows.GetKeyState(VK_CONTROL) < 0) then { if the CTRL key is pressed }
    ImageEnView1.MouseInteractGeneral := [miScroll]
  else
    ImageEnView1.MouseInteractGeneral := [miSelect];
end;