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From: smoke@well.sf.ca.us (Nicholas Jackiw)
Newsgroups: comp.sys.mac.programmer
Subject: Standard File help needed
Message-ID: <21010@well.sf.ca.us>
Date: 5 Oct 90 22:54:07 GMT
Sender: smoke@well.sf.ca.us
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 49



Can anyone give me a hand with some Standard File magic?
I'd like to implement an Open All button in the SFGetFile
dialog.  As usual, this should be dimmed if the currently
viewed folder does not contain any files of the appropriate
fType. The obvious way to go about this is to have the
dialog hook disable the button everytime a new directory
appears, and then have the file-filter re-enable it (if
the filter is called, obviously there's a file of fType
sitting in the directory).

Unfortunately, I can't seem to find a reliable method
for determining when the directory has changed. Things
that I've tried:

o Monitoring CurDirStore

This changes erratically during directory browsing, but not
reliably.

o Monitoring SFSaveDisk

This doesn't seem to change at all (except perhaps once at the
very end of the dialog).

o Monitoring theReply.vRefNum

This only gets instantiated at the end of the dialog, and is
zero before then.

o Watching which items the user hits

As of IM-IV, the hook will see changes in directory when the
user clicks or opens a folder as item#103, and can detect
clicks on the Drive button as item#6.  However, one can 
also navigate between directories with cmd-up and cmd-down,
and with the pop-up menu of "open" directories.  While you
can tell when one of these events occur, you can't (based
on the item number) tell whether it caused a change in the
active directory (and therefore, reason to dim the Open All
control).

---

I'm a bit befuddled at what should be a straightforward task.
In that 7.0 revises Standard File somewhat, I'd like to find
a scheme with good chances of surviving the future.  Any
hints would be appreciated.