bpo-41043: Escape literal part of the path for glob(). (GH-20994)

diff --git a/Lib/idlelib/tree.py b/Lib/idlelib/tree.py
index 6229be4..5947268 100644
--- a/Lib/idlelib/tree.py
+++ b/Lib/idlelib/tree.py
@@ -38,7 +38,7 @@
     """Utility to display the available icons."""
     root = Tk()
     import glob
-    list = glob.glob(os.path.join(icondir, "*.gif"))
+    list = glob.glob(os.path.join(glob.escape(icondir), "*.gif"))
     list.sort()
     images = []
     row = column = 0