From a3da152cb56641c452bcd973e46f7b473824b1bd Mon Sep 17 00:00:00 2001
From: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
Date: Sat, 25 May 2019 08:24:29 +0200
Subject: [PATCH] Backport PR #14319: Don't set missing history buttons.

---
 lib/matplotlib/backends/backend_gtk3.py | 6 ++++--
 lib/matplotlib/backends/backend_qt5.py  | 6 ++++--
 lib/matplotlib/backends/backend_wx.py   | 6 ++++--
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/lib/matplotlib/backends/backend_gtk3.py b/lib/matplotlib/backends/backend_gtk3.py
index 9f6d1f693c29..034bb6baae87 100644
--- a/lib/matplotlib/backends/backend_gtk3.py
+++ b/lib/matplotlib/backends/backend_gtk3.py
@@ -611,8 +611,10 @@ def _get_canvas(self, fig):
     def set_history_buttons(self):
         can_backward = self._nav_stack._pos > 0
         can_forward = self._nav_stack._pos < len(self._nav_stack._elements) - 1
-        self._gtk_ids['Back'].set_sensitive(can_backward)
-        self._gtk_ids['Forward'].set_sensitive(can_forward)
+        if 'Back' in self._gtk_ids:
+            self._gtk_ids['Back'].set_sensitive(can_backward)
+        if 'Forward' in self._gtk_ids:
+            self._gtk_ids['Forward'].set_sensitive(can_forward)
 
 
 @cbook.deprecated("3.1")
diff --git a/lib/matplotlib/backends/backend_qt5.py b/lib/matplotlib/backends/backend_qt5.py
index 7dc25faaff22..c03c7771c918 100644
--- a/lib/matplotlib/backends/backend_qt5.py
+++ b/lib/matplotlib/backends/backend_qt5.py
@@ -851,8 +851,10 @@ def save_figure(self, *args):
     def set_history_buttons(self):
         can_backward = self._nav_stack._pos > 0
         can_forward = self._nav_stack._pos < len(self._nav_stack._elements) - 1
-        self._actions['back'].setEnabled(can_backward)
-        self._actions['forward'].setEnabled(can_forward)
+        if 'back' in self._actions:
+            self._actions['back'].setEnabled(can_backward)
+        if 'forward' in self._actions:
+            self._actions['forward'].setEnabled(can_forward)
 
 
 class SubplotToolQt(UiSubplotTool):
diff --git a/lib/matplotlib/backends/backend_wx.py b/lib/matplotlib/backends/backend_wx.py
index 95499700ccc2..6ee48484ccbb 100644
--- a/lib/matplotlib/backends/backend_wx.py
+++ b/lib/matplotlib/backends/backend_wx.py
@@ -1567,8 +1567,10 @@ def set_message(self, s):
     def set_history_buttons(self):
         can_backward = self._nav_stack._pos > 0
         can_forward = self._nav_stack._pos < len(self._nav_stack._elements) - 1
-        self.EnableTool(self.wx_ids['Back'], can_backward)
-        self.EnableTool(self.wx_ids['Forward'], can_forward)
+        if 'Back' in self.wx_ids:
+            self.EnableTool(self.wx_ids['Back'], can_backward)
+        if 'Forward' in self.wx_ids:
+            self.EnableTool(self.wx_ids['Forward'], can_forward)
 
 
 class StatusBarWx(wx.StatusBar):