Graphics protocol: Only delete temp files if they have the string tty-graphics-protocol in their file paths.

This prevents deletion of arbitrary files in /tmp via the graphics
protocol.

docs/changelog.rst

@@ -44,6 +44,9 @@ Detailed list of changes
 
 - A new option :opt:`modify_font` to adjust various font metrics like underlines, cell sizes etc. (:pull:`5265`)
 
+- Graphics protocol: Only delete temp files if they have the string
+  :code:`tty-graphics-protocol` in their file paths. This prevents deletion of arbitrary files in :file:`/tmp`.
+
 - Deprecate the ``adjust_baseline``, ``adjust_line_height`` and ``adjust_column_width`` options in favor of :opt:`modify_font`
 
 - Wayland: Fix a regression in the previous release that caused mouse cursor

docs/graphics-protocol.rst

@@ -237,7 +237,8 @@ Value of `t`          Meaning
                       the terminal emulator should only delete the file if it
                       is in a known temporary directory, such as :file:`/tmp`,
                       :file:`/dev/shm`, :file:`TMPDIR env var if present` and any platform
-                      specific temporary directories.
+                      specific temporary directories and the file has the
+                      string :code:`tty-graphics-protocol` in its full file path.
 ``s``                 A *shared memory object*, which on POSIX systems is a
                       `POSIX shared memory object <https://pubs.opengroup.org/onlinepubs/9699919799/functions/shm_open.html>`_
                       and on Windows is a