1. Catch NameError on import (could be raised by case mismatch on Windows).

2. No longer need to reset pyclbr cache and show watch cursor when calling
   ClassBrowser -- the ClassBrowser takes care of pyclbr and the TreeWidget
   takes care of the watch cursor.
3. Reset the focus to the current window after error message about class
   browser on buffer without filename.

Tools/idle/EditorWindow.py

@@ -295,7 +295,7 @@ class EditorWindow:
         # XXX Ought to insert current file's directory in front of path
         try:
             (f, file, (suffix, mode, type)) = imp.find_module(name)
-        except ImportError, msg:
+        except (NameError, ImportError), msg:
             tkMessageBox.showerror("Import error", str(msg), parent=self.text)
             return
         if type != imp.PY_SOURCE:
@@ -316,18 +316,12 @@ class EditorWindow:
                 "No filename",
                 "This buffer has no associated filename",
                 master=self.text)
+            self.text.focus_set()
             return None
         head, tail = os.path.split(filename)
         base, ext = os.path.splitext(tail)
-        import pyclbr
-        if pyclbr._modules.has_key(base):
-            del pyclbr._modules[base]
-        save_cursor = self.text["cursor"]
-        self.text["cursor"] = "watch"
-        self.text.update_idletasks()
         import ClassBrowser
         ClassBrowser.ClassBrowser(self.flist, base, [head])
-        self.text["cursor"] = save_cursor
 
     def open_path_browser(self, event=None):
         import PathBrowser