[PyMOL] Bug in Save Molecule dialog box

Hi,
I've discovered a (relatively minor) bug in the Save Molecule... dialog 
box. This happened because I always have tons of windows up on multiple 
monitors and it got lost.

To reproduce:
Go to File > Save Molecule...
Don't close the window, and do it again
Go to File > Save Molecule...

Now you can close one of the dialogs by hitting Cancel as usual. Now if 
you hit Cancel or Ok or the X in the corner on the other dialog, it 
throw an error, and you can't get it to close without closing the parent 
pymol session.

Error: 2
<type 'exceptions.AttributeError'> Exception in Tk callback
   Function: <function <lambda> at 0x7fc557515848> (type: <type 'function'>)
   Args: ()
Traceback (innermost last):
   File "/usr/lib/python2.7/dist-packages/Pmw/Pmw_1_3/lib/PmwBase.py", 
line 1747, in __call__
     return apply(self.func, args)
   File "/usr/lib/python2.7/dist-packages/Pmw/Pmw_1_3/lib/PmwDialog.py", 
line 153, in <lambda>
     command=lambda self=self, name=name: self._doCommand(name))
   File "/usr/lib/python2.7/dist-packages/Pmw/Pmw_1_3/lib/PmwDialog.py", 
line 132, in _doCommand
     return command(name)
   File 
"/usr/local/lib/python2.7/dist-packages/pmg_tk/skins/normal/__init__.py", line 
792, in file_save2
     self.my_withdraw(self.dialog)
<type 'exceptions.AttributeError'>: Normal instance has no attribute 
'dialog'



Most of the errors appear to be in the Pwm code, which you obviously 
don't control. I haven't dived into the code myself, but I think that 
you can catch this by detecting when the dialog is open and if another 
one tries to open, call raise() on the original one.

I'm running pymol 1.7.4.0, revision 4107 from the SVN built from source 
on Ubuntu 14.04.