ChosenPic := FileList.ItemIndex;
if not PicLoaded Then
Exit;
if ChosenPic <= 0 then
ChosenPic := FileList.Count -1
else if ChosenPic > FileList.Count -1 then
ChosenPic := 0
else
Dec(ChosenPic);
FileList.ItemIndex := ChosenPic;
Filename := ExtractFileDir(FileName) + CDash + FileList.Items.Strings[ChosenPic];
PicName := ExtractFileName(FileName);
PicExt := ExtractFileExt(FileName);
imgMain.Picture.LoadFromFile(FileName);