Closing side view panel gives error.

[Tom Goddard]

Pressing the close window button on the side view panel gives the following error to the shell (not to the reply log).

$ ~/ucsf/chimera2/Chimera2.app/Contents/MacOS/Chimera2
Using 24-bit OpenGL depth buffer
Stereo mode is not supported by OpenGL driver
Traceback (most recent call last):

File "/Users/goddard/ucsf/chimera2/Chimera2.app/Contents/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages/chimera/core/gui.py", line 168, in OnPaneClose

tool_window.destroy(from_destructor=True)

File "/Users/goddard/ucsf/chimera2/Chimera2.app/Contents/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages/chimera/core/gui.py", line 343, in destroy

self.toolkit.destroy(kw)

File "/Users/goddard/ucsf/chimera2/Chimera2.app/Contents/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages/chimera/core/gui.py", line 403, in destroy

del self.main_window.tool_pane_to_window[self.ui_area]

KeyError: <chimera.core.gui._Wx.init.<locals>.WxToolPanel object at 0x110929ea0>

[Greg Couch]

In [develop 97e6ec4], put in try/except workaround in _Wx.destroy from core/gui.py.

Pass to Eric for code review.

[Eric Pettersen]

Changed the workaround to the more permanent fix of preventing the double removal.