From 7cedabc79a3e85c54716444e1337cf97fec7a43b Mon Sep 17 00:00:00 2001
From: Matthew Newville <newville@cars.uchicago.edu>
Date: Thu, 5 Jan 2017 20:46:58 -0600
Subject: [PATCH] ensure mouse is always released on loss of focus and before
 trying to re-capture

---
 lib/matplotlib/backends/backend_wx.py | 35 ++++++++++++++++++---------
 1 file changed, 23 insertions(+), 12 deletions(-)

diff --git a/lib/matplotlib/backends/backend_wx.py b/lib/matplotlib/backends/backend_wx.py
index ecd3bf970ad1..b050bb5f7299 100644
--- a/lib/matplotlib/backends/backend_wx.py
+++ b/lib/matplotlib/backends/backend_wx.py
@@ -685,6 +685,9 @@ def do_nothing(*args, **kwargs):
         self.Bind(wx.EVT_MIDDLE_DCLICK, self._onMiddleButtonDClick)
         self.Bind(wx.EVT_MIDDLE_UP, self._onMiddleButtonUp)
 
+        self.Bind(wx.EVT_MOUSE_CAPTURE_CHANGED, self._onCaptureLost)
+        self.Bind(wx.EVT_MOUSE_CAPTURE_LOST, self._onCaptureLost)
+
         if wx.VERSION_STRING < "2.9":
             # only needed in 2.8 to reduce flicker
             self.SetBackgroundStyle(wx.BG_STYLE_CUSTOM)
@@ -1023,12 +1026,23 @@ def _onKeyUp(self, evt):
         evt.Skip()
         FigureCanvasBase.key_release_event(self, key, guiEvent=evt)
 
+    def _set_capture(self, capture=True):
+        """control wx mouse capture """
+        if self.HasCapture():
+            self.ReleaseMouse()
+        if capture:
+            self.CaptureMouse()
+
+    def _onCaptureLost(self, evt):
+        """Capture changed or lost"""
+        self._set_capture(False)
+
     def _onRightButtonDown(self, evt):
         """Start measuring on an axis."""
         x = evt.GetX()
         y = self.figure.bbox.height - evt.GetY()
         evt.Skip()
-        self.CaptureMouse()
+        self._set_capture(True)
         FigureCanvasBase.button_press_event(self, x, y, 3, guiEvent=evt)
 
     def _onRightButtonDClick(self, evt):
@@ -1036,7 +1050,7 @@ def _onRightButtonDClick(self, evt):
         x = evt.GetX()
         y = self.figure.bbox.height - evt.GetY()
         evt.Skip()
-        self.CaptureMouse()
+        self._set_capture(True)
         FigureCanvasBase.button_press_event(self, x, y, 3,
                                             dblclick=True, guiEvent=evt)
 
@@ -1045,8 +1059,7 @@ def _onRightButtonUp(self, evt):
         x = evt.GetX()
         y = self.figure.bbox.height - evt.GetY()
         evt.Skip()
-        if self.HasCapture():
-            self.ReleaseMouse()
+        self._set_capture(False)
         FigureCanvasBase.button_release_event(self, x, y, 3, guiEvent=evt)
 
     def _onLeftButtonDown(self, evt):
@@ -1054,7 +1067,7 @@ def _onLeftButtonDown(self, evt):
         x = evt.GetX()
         y = self.figure.bbox.height - evt.GetY()
         evt.Skip()
-        self.CaptureMouse()
+        self._set_capture(True)
         FigureCanvasBase.button_press_event(self, x, y, 1, guiEvent=evt)
 
     def _onLeftButtonDClick(self, evt):
@@ -1062,7 +1075,7 @@ def _onLeftButtonDClick(self, evt):
         x = evt.GetX()
         y = self.figure.bbox.height - evt.GetY()
         evt.Skip()
-        self.CaptureMouse()
+        self._set_capture(True)
         FigureCanvasBase.button_press_event(self, x, y, 1,
                                             dblclick=True, guiEvent=evt)
 
@@ -1072,8 +1085,7 @@ def _onLeftButtonUp(self, evt):
         y = self.figure.bbox.height - evt.GetY()
         # print 'release button', 1
         evt.Skip()
-        if self.HasCapture():
-            self.ReleaseMouse()
+        self._set_capture(False)
         FigureCanvasBase.button_release_event(self, x, y, 1, guiEvent=evt)
 
     # Add middle button events
@@ -1082,7 +1094,7 @@ def _onMiddleButtonDown(self, evt):
         x = evt.GetX()
         y = self.figure.bbox.height - evt.GetY()
         evt.Skip()
-        self.CaptureMouse()
+        self._set_capture(True)
         FigureCanvasBase.button_press_event(self, x, y, 2, guiEvent=evt)
 
     def _onMiddleButtonDClick(self, evt):
@@ -1090,7 +1102,7 @@ def _onMiddleButtonDClick(self, evt):
         x = evt.GetX()
         y = self.figure.bbox.height - evt.GetY()
         evt.Skip()
-        self.CaptureMouse()
+        self._set_capture(True)
         FigureCanvasBase.button_press_event(self, x, y, 2,
                                             dblclick=True, guiEvent=evt)
 
@@ -1100,8 +1112,7 @@ def _onMiddleButtonUp(self, evt):
         y = self.figure.bbox.height - evt.GetY()
         # print 'release button', 1
         evt.Skip()
-        if self.HasCapture():
-            self.ReleaseMouse()
+        self._set_capture(False)
         FigureCanvasBase.button_release_event(self, x, y, 2, guiEvent=evt)
 
     def _onMouseWheel(self, evt):