Issue #20338: Increase allowed tip width slightly and wrap long signagure lines.

Original patch by Serhiy Storchaka.

diff --cc Lib/idlelib/idle_test/test_calltips.py
index eca24ec129396d5403993091fc61d5f80f32a251,e71656b6aed773323a36ce3bc15e650a3c2ade4d..f27994f3f97c3dd884e7696d5484cf2d5387c612
--- 1/Lib/idlelib/idle_test/test_calltips.py
--- 2/Lib/idlelib/idle_test/test_calltips.py
+++ b/Lib/idlelib/idle_test/test_calltips.py
@@@ -64,6 -65,17 +65,19 @@@ class Get_signatureTest(unittest.TestCa
          gtest(types.MethodType, "method(function, instance)")
          gtest(SB(), default_tip)
  
 -    drop_whitespace=True, break_on_hyphens=True, tabsize=8)''')
+     def test_signature_wrap(self):
++        #print(signature(textwrap.TextWrapper))
+         self.assertEqual(signature(textwrap.TextWrapper), '''\
+ (width=70, initial_indent='', subsequent_indent='', expand_tabs=True,
+     replace_whitespace=True, fix_sentence_endings=False, break_long_words=True,
++    drop_whitespace=True, break_on_hyphens=True, tabsize=8, *, max_lines=None,
++    placeholder=' [...]')''')
+ 
+     def test_docline_truncation(self):
+         def f(): pass
+         f.__doc__ = 'a'*300
+         self.assertEqual(signature(f), '()\n' + 'a' * (ct._MAX_COLS-3) + '...')
+ 
      def test_multiline_docstring(self):
          # Test fewer lines than max.
          self.assertEqual(signature(list),