Issue #25464: Fixed HList.header_exists() in tkinter.tix module by addin

a workaround to Tix library bug.

Lib/tkinter/tix.py

@@ -926,7 +926,11 @@ class HList(TixWidget, XView, YView):
         return self.tk.call(self._w, 'header', 'cget', col, opt)
 
     def header_exists(self,  col):
-        return self.tk.call(self._w, 'header', 'exists', col)
+        # A workaround to Tix library bug (issue #25464).
+        # The documented command is "exists", but only erroneous "exist" is
+        # accepted.
+        return self.tk.getboolean(self.tk.call(self._w, 'header', 'exist', col))
+    header_exist = header_exists
 
     def header_delete(self, col):
         self.tk.call(self._w, 'header', 'delete', col)

Misc/NEWS

@@ -23,6 +23,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #25464: Fixed HList.header_exists() in tkinter.tix module by addin
+  a workaround to Tix library bug.
+
 - Issue #28488: shutil.make_archive() no longer adds entry "./" to ZIP archive.
 
 - Issue #25953: re.sub() now raises an error for invalid numerical group