move wxapp creation to show()

svn path=/trunk/matplotlib/; revision=1076

Author: newville

lib/matplotlib/backends/backend_wx.py

@@ -113,8 +113,8 @@
     print >>sys.stderr, "Matplotlib backend_wx requires wxPython be installed"
     sys.exit()    
 
-wxapp = wxPySimpleApp()
-wxapp.SetExitOnFrameDelete(True)
+# wxapp = wxPySimpleApp()
+# wxapp.SetExitOnFrameDelete(True)
 
 
 #!!! this is the call that is causing the exception swallowing !!!
@@ -1156,6 +1156,8 @@ def show():
         figwin.canvas.draw()
 
     if show._needmain and not matplotlib.is_interactive():
+        wxapp = wx.PySimpleApp()
+        wxapp.SetExitOnFrameDelete(True)
         wxapp.MainLoop()
         show._needmain = False        
 show._needmain = True