From 2ddb364a015d66a3f3c39fd42cb5f3083409f18d Mon Sep 17 00:00:00 2001
From: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
Date: Thu, 20 Mar 2025 19:00:17 +0100
Subject: [PATCH] Backport PR #29781: Fix escaping of nulls and "0" in default
 filenames.

---
 lib/matplotlib/backend_bases.py            | 17 +++++++++--------
 lib/matplotlib/tests/test_backend_bases.py |  5 ++++-
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
index 0843796bad5a..a889a6b26e8e 100644
--- a/lib/matplotlib/backend_bases.py
+++ b/lib/matplotlib/backend_bases.py
@@ -2218,7 +2218,7 @@ def get_default_filename(self):
         # Characters to be avoided in a NT path:
         # https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx#naming_conventions
         # plus ' '
-        removed_chars = r'<>:"/\|?*\0 '
+        removed_chars = '<>:"/\\|?*\0 '
         default_basename = default_basename.translate(
             {ord(c): "_" for c in removed_chars})
         default_filetype = self.get_default_filetype()
@@ -2728,23 +2728,24 @@ def resize(self, w, h):
         """For GUI backends, resize the window (in physical pixels)."""
 
     def get_window_title(self):
-        """
-        Return the title text of the window containing the figure, or None
-        if there is no window (e.g., a PS backend).
-        """
-        return 'image'
+        """Return the title text of the window containing the figure."""
+        return self._window_title
 
     def set_window_title(self, title):
         """
         Set the title text of the window containing the figure.
 
-        This has no effect for non-GUI (e.g., PS) backends.
-
         Examples
         --------
         >>> fig = plt.figure()
         >>> fig.canvas.manager.set_window_title('My figure')
         """
+        # This attribute is not defined in __init__ (but __init__ calls this
+        # setter), as derived classes (real GUI managers) will store this
+        # information directly on the widget; only the base (non-GUI) manager
+        # class needs a specific attribute for it (so that filename escaping
+        # can be checked in the test suite).
+        self._window_title = title
 
 
 cursors = tools.cursors
diff --git a/lib/matplotlib/tests/test_backend_bases.py b/lib/matplotlib/tests/test_backend_bases.py
index 3e1f524ed1c9..10108d11bd0a 100644
--- a/lib/matplotlib/tests/test_backend_bases.py
+++ b/lib/matplotlib/tests/test_backend_bases.py
@@ -64,7 +64,10 @@ def test_canvas_ctor():
 
 
 def test_get_default_filename():
-    assert plt.figure().canvas.get_default_filename() == 'image.png'
+    fig = plt.figure()
+    assert fig.canvas.get_default_filename() == "Figure_1.png"
+    fig.canvas.manager.set_window_title("0:1/2<3")
+    assert fig.canvas.get_default_filename() == "0_1_2_3.png"
 
 
 def test_canvas_change():