Merge pull request #7052 from anntzer/catch-exceptions-in-qt5-draw-pr…

…events-abort

FIX: Uncaught exns are fatal for PyQt5, so catch them.

lib/matplotlib/backends/backend_qt5agg.py

@@ -6,8 +6,9 @@
 
 from matplotlib.externals import six
 
-import sys
 import ctypes
+import sys
+import traceback
 
 from matplotlib.figure import Figure
 
@@ -178,6 +179,9 @@ def __draw_idle_agg(self, *args):
         try:
             FigureCanvasAgg.draw(self)
             self.update()
+        except Exception:
+            # Uncaught exceptions are fatal for PyQt5, so catch them instead.
+            traceback.print_exc()
         finally:
             self._agg_draw_pending = False