More idlelib cleanup inspired by pyflakes.

Lib/idlelib/SearchEngine.py

@@ -85,7 +85,7 @@ class SearchEngine:
         except re.error as what:
             args = what.args
             msg = args[0]
-            col = arg[1] if len(args) >= 2 else -1
+            col = args[1] if len(args) >= 2 else -1
             self.report_error(pat, msg, col)
             return None
         return prog

Lib/idlelib/StackViewer.py

@@ -131,8 +131,8 @@ def _stack_viewer(parent):
     root.geometry("+%d+%d"%(x, y + 150))
     flist = PyShellFileList(root)
     try: # to obtain a traceback object
-        a
-    except:
+        intentional_name_error
+    except NameError:
         exc_type, exc_value, exc_tb = sys.exc_info()
 
     # inject stack trace to sys

Lib/idlelib/idle_test/test_textview.py

@@ -12,7 +12,7 @@ requires('gui')
 
 import unittest
 import os
-from tkinter import Tk, Text, TclError
+from tkinter import Tk
 from idlelib import textView as tv
 from idlelib.idle_test.mock_idle import Func
 from idlelib.idle_test.mock_tk import Mbox
@@ -23,7 +23,7 @@ def setUpModule():
 
 def tearDownModule():
     global root
-    root.destroy()
+    root.destroy()  # pyflakes falsely sees root as undefined
     del root