On Mac, closing last window quits the program

[ghutchis]

On the Mac OSX port the close buttons quits the program rather than clearing the current molecule.

Reported by: dcurtis3

[ghutchis]

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This was followed on the mailing list:
http://sourceforge.net/mailarchive/forum.php?thread_name=E1Hojmk-0007Cq-8D%40sc8-sf-web21.sourceforge.net&forum_name=avogadro-devel

On the Mac, we need to keep one remaining MainWindow open unless we choose to quit.

Original comment by: @ghutchis

[ghutchis]

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This is now fixed in the SVN trunk, revision 462 or later. (This fix also removes menu icons on Mac.)

The fix hasn't had much testing -- there may be additional interface consistency bugs, but it's a good start, IMHO.

Original comment by: @ghutchis