At bottom of http://bugzilla.audacityteam.org/show_bug.cgi?id=137#c17:
> I noticed that although when we open the same project a second time with File >
> Open or File > Recent Files we show an error "is already open in another
> window", there is no block on executing the .aup from your file manager and
> opening as many copies of the project as you like. I had not done that when
> Audacity moved the files around in error the first time, but can we block this
> anyway?
This is a different bug from Bug 137, repeatable, and I think lower priority. But I went ahead and fixed it with this commit.
Also fixed previously unnoted bug where AudacityApp::MRUOpen() returned true when it actually failed to open the file. Also removed AudacityApp::OnMRUProject() cruft.
Unfortunately, it still creates a new, empty project window on Win Explorer open whereas Open and Recent Files commands do not. I think that constitutes a new, separate P5 bug.
Overall, this is another aspect of what I was talking about in http://bugzilla.audacityteam.org/show_bug.cgi?id=322#c26. Opening files vs projects got conflated for convenience, but this code is hacked in some regards, rather than being a good design, and that's why this type of bug shows up.
2. Save user's preference for enabling linking
3. fix a bug by which changes to global prefs like SWPlaythrough were not
visually reflected in other open projects.
