matplotlib
diff --git a/‎lib/matplotlib/backend_bases.py
Lines changed: 34 additions & 2 deletions b/‎lib/matplotlib/backend_bases.py
Lines changed: 34 additions & 2 deletions
diff --git a/‎lib/matplotlib/backends/backend_qt5.py
Lines changed: 6 additions & 6 deletions b/‎lib/matplotlib/backends/backend_qt5.py
Lines changed: 6 additions & 6 deletions
@@ -1372,6 +1372,8 @@ class MouseButton(IntEnum):
     LEFT = 1
     MIDDLE = 2
     RIGHT = 3
+    X1 = 4
+    X2 = 5
 
 
 class MouseEvent(LocationEvent):
@@ -2394,6 +2396,17 @@ def _get_uniform_gridstate(ticks):
                     a.set_navigate(i == n)
 
 
+def button_press_handler(event, canvas, toolbar=None):
+    """
+    The default Matplotlib button actions for extra mouse buttons.
+    """
+    if toolbar is not None:
+        if event.button is MouseButton.X1:
+            toolbar.back()
+        elif event.button is MouseButton.X2:
+            toolbar.forward()
+
+
 class NonGuiException(Exception):
     pass
 
@@ -2411,22 +2424,34 @@ class FigureManagerBase(object):
         The figure number
 
     key_press_handler_id : int
-        The default key handler cid, when using the toolmanager.  Can be used
-        to disable default key press handling ::
+        The default key handler cid, when using the toolmanager.
+        To disable the default key press handling use::
 
             figure.canvas.mpl_disconnect(
                 figure.canvas.manager.key_press_handler_id)
+
+    button_press_handler_id : int
+        The default mouse button handler cid, when using the toolmanager.
+        To disable the default button press handling use::
+
+            figure.canvas.mpl_disconnect(
+                figure.canvas.manager.button_press_handler_id)
+
     """
     def __init__(self, canvas, num):
         self.canvas = canvas
         canvas.manager = self  # store a pointer to parent
         self.num = num
 
         self.key_press_handler_id = None
+        self.button_press_handler_id = None
         if rcParams['toolbar'] != 'toolmanager':
             self.key_press_handler_id = self.canvas.mpl_connect(
                 'key_press_event',
                 self.key_press)
+            self.button_press_handler_id = self.canvas.mpl_connect(
+                'button_press_event',
+                self.button_press)
 
         self.toolmanager = None
         self.toolbar = None
@@ -2463,6 +2488,13 @@ def key_press(self, event):
         if rcParams['toolbar'] != 'toolmanager':
             key_press_handler(event, self.canvas, self.canvas.toolbar)
 
+    def button_press(self, event):
+        """
+        The default Matplotlib button actions for extra mouse buttons.
+        """
+        if rcParams['toolbar'] != 'toolmanager':
+            button_press_handler(event, self.canvas, self.canvas.toolbar)
+
     @cbook.deprecated("2.2")
     def show_popup(self, msg):
         """Display message in a popup -- GUI only."""
 
@@ -11,7 +11,7 @@
 from matplotlib._pylab_helpers import Gcf
 from matplotlib.backend_bases import (
     _Backend, FigureCanvasBase, FigureManagerBase, NavigationToolbar2,
-    TimerBase, cursors, ToolContainerBase, StatusbarBase)
+    TimerBase, cursors, ToolContainerBase, StatusbarBase, MouseButton)
 import matplotlib.backends.qt_editor.figureoptions as figureoptions
 from matplotlib.backends.qt_editor.formsubplottool import UiSubplotTool
 from matplotlib.backend_managers import ToolManager
@@ -213,11 +213,11 @@ def _timer_stop(self):
 class FigureCanvasQT(QtWidgets.QWidget, FigureCanvasBase):
 
     # map Qt button codes to MouseEvent's ones:
-    buttond = {QtCore.Qt.LeftButton: 1,
-               QtCore.Qt.MidButton: 2,
-               QtCore.Qt.RightButton: 3,
-               # QtCore.Qt.XButton1: None,
-               # QtCore.Qt.XButton2: None,
+    buttond = {QtCore.Qt.LeftButton: MouseButton.LEFT,
+               QtCore.Qt.MidButton: MouseButton.MIDDLE,
+               QtCore.Qt.RightButton: MouseButton.RIGHT,
+               QtCore.Qt.XButton1: MouseButton.X1,
+               QtCore.Qt.XButton2: MouseButton.X2,
                }
 
     @_allow_super_init