procedure TForm1.ImageEnMView1MouseDown(Sender: TObject; Button: System.UITypes.TMouseButton; Shift: TShiftState; X, Y: Integer);
var
  ScreenPoint: TPoint;
begin
  if Button = Vcl.Controls.mbRight then
  begin
    // Get the index of the image cell at the mouse position?
    // ImageEnMView1.SelectImage(ImageEnMView1.MouseDownThumbIndex);

    // Convert the mouse position of the clicked control to screen coordinates:
    ScreenPoint := ImageEnMView1.ClientToScreen(Point(X, Y));
    // Show the popup menu at the mouse position:
    PopupMenuOptions.Popup(ScreenPoint.X, ScreenPoint.Y);
  end;
end;