OK, finally found the problem with my application's use of "open
file". Its appears that the problem is due to an incorrect "open
file" entry in NSCoreSuite.sdef.
I filed a bug rdar://4725273
In short, the default NSApplication handler
(handleOpenScriptCommand:) expects the direct parameter to be a list
of files, but the sdef has the implicit "list="no".
If you change the open command to be:
<command name="open" code="aevtodoc" description="Open an object.">
<direct-parameter description="The file(s) to be opened." type="file"
list="yes"/>
</command>
then everything starts working [the change is the addition of list="yes"].
