Ohhhh ok-- now i understand...
Yes, you are right. i could do it without checking..
But if for example.. i post the product as hack here,
and a user installs it.., it works..
then for some reason he uninstalls vbgallery... because (for example he switches to photopost pro), he would still get links to vbgallery files and send his users to 404 pages.. thats why i want to do the check..