Backport Python Patches 769142, 776062 from 2.3 Lib/idlelib:

kbkaiser · kbkaiser · commit 75c9877789c5 · 2003-07-23T16:25:43.000Z
CallTip error when docstring contains only \n and/or \t
diff --git a/Tools/idle/CallTips.py b/Tools/idle/CallTips.py
@@ -148,8 +148,7 @@ def get_arg_text(ob):
         # See if we can use the docstring
         doc = getattr(ob, "__doc__", "")
         if doc:
-            while doc[:1] in " \t\n":
-                doc = doc[1:]
+            doc = doc.lstrip()
             pos = doc.find("\n")
             if pos < 0 or pos > 70:
                 pos = 70
