procedure TMainForm.ImageEnView1MouseWheel(Sender: TObject; Shift: TShiftState;
    WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
begin
  if WheelDelta < 0 then
    fCurrentImage := max( 0, fCurrentImage - 1 )
  else
    fCurrentImage := min( ImageEnMView1.ImageCount - 1, fCurrentImage - 1 );

  ImageEnMView1.CopyToIEBitmap( fCurrentImage, ImageEnView1.IEBitmap );
  ImageEnView1.Update;
end;

if WheelDelta <= 0 then
    begin
      ImageEnFolderMView1.SelectedImage:= ImageEnFolderMView1.SelectedImage-1;
    end
  else
    begin
      ImageEnFolderMView1.SelectedImage:= ImageEnFolderMView1.SelectedImage+1;
    end;
  ImageEnView1.IO.LoadFromFile(ImageEnFolderMView1.SelectedFilename);