The "Show Script menu in menu bar" box
must be checked in AppleScript Utility.
Check it now, if necessary,
then close AppleScript Utility.
An AppleScripter will see what is happening, and choose "Cancel" every time.
But my user's (and yours) have probably never heard of AppleScript and will simply be very confused. They will invariably, at some point, choose any old application from the list.
The "Where is ... ?" dialog opens the inner workings of an AppleScript-ed application to permanent damage. In BOTH Tiger and Leopard. It's just that in Leopard, I can avoid the dialog by using 'application id'.
THE "Where is ... ?" DIALOG MUST BE AVOIDED. BETTER YET, IT SHOULD NOT EVEN BE PRESENT IN THE NEXT VERSION OF APPLESCRIPT. IT'S DANGEROUS.
But, how can I avoid the "Where is ... ?" dialog in Tiger? I don't think I can.
(But, perhaps someone knows more about this?)
I will probably have to simply present the dialog ...
If the Script menu is not visible in the menu bar,
launch AppleScript Utility, in the AppleScript folder
in the Applications folder, then check the box
"Show Script menu in menu bar".
Some will read and comply, others will just not get it.
If you want to experiment with this in Leopard, use this ...