Issue #24972: New option is only valid in tk 8.5+.

diff --git a/Lib/idlelib/EditorWindow.py b/Lib/idlelib/EditorWindow.py
index 1f4bd9dd62b320c0863974ec5a531a7a666cf78d..1243b95417a32d9b51d816299387bb645bfa53a3 100644 (file)
--- a/Lib/idlelib/EditorWindow.py
+++ b/Lib/idlelib/EditorWindow.py
@@ -770,8 +770,10 @@ class EditorWindow(object):
             insertbackground=cursor_color,
             selectforeground=select_colors['foreground'],
             selectbackground=select_colors['background'],
-            inactiveselectbackground=select_colors['background'],
             )
+        if TkVersion >= 8.5:
+            self.text.config(
+                inactiveselectbackground=select_colors['background'])
 
     def ResetFont(self):
         "Update the text widgets' font if it is changed"