Merge pull request matplotlib#1678 from tacaswell/qt4_closeevent

added QtGui.QMainWindow.closeEvent() to make sure the close event

Author: dmcdougall

lib/matplotlib/backends/backend_qt4.py

@@ -370,6 +370,7 @@ def idle_draw(*args):
 class MainWindow(QtGui.QMainWindow):
     def closeEvent(self, event):
         self.emit(QtCore.SIGNAL('closing()'))
+        QtGui.QMainWindow.closeEvent(self, event)
 
 class FigureManagerQT( FigureManagerBase ):
     """