If you need to check for the presence of Acrobat before launching PDFs in your publications, here is a method for doing so. The only caveat for this method is that Windows 2000 puts the registry entry in by default, so this won't work on Windows 2000, but from what I have read, there really is no foolproof method for discovering whether Acrobat is on a machine.
This can go on a Page action on show. The b's referred to below in the code are buttons. One to launch a PDF, the other to go to Acrobat downloader. They are both set to be initially hidden.
Hope this helps folks.
Code:
var AcroInst = ReadRegistryKey("HKEY_CLASSES_ROOT\\.pdf", "Content Type");
if(AcroInst=='application/pdf'){
b1.Show();
}
else {
b2.Show();
}