Support underlining of menu labels

Tools/idle/EditorWindow.py

@@ -82,17 +82,18 @@ class EditorWindow:
         self.saved_change_hook()
 
     menu_specs = [
-        ("file", "File"),
-        ("edit", "Edit"),
-        ("help", "Help"),
+        ("file", "_File"),
+        ("edit", "_Edit"),
+        ("help", "_Help"),
     ]
 
     def createmenubar(self):
         mbar = self.menubar
         self.menudict = mdict = {}
         for name, label in self.menu_specs:
+            underline, label = self.Bindings.prepstr(label)
             mdict[name] = menu = Menu(mbar, name=name)
-            mbar.add_cascade(label=label, menu=menu)
+            mbar.add_cascade(label=label, menu=menu, underline=underline)
         self.Bindings.fill_menus(self.text, mdict)
 
     def about_dialog(self, event=None):

Tools/idle/FileList.py

@@ -21,7 +21,7 @@ class MultiEditorWindow(EditorWindow):
     
     # Override menu bar specs
     menu_specs = EditorWindow.menu_specs[:]
-    menu_specs.insert(len(menu_specs)-1, ("windows", "Windows"))
+    menu_specs.insert(len(menu_specs)-1, ("windows", "_Windows"))
 
     def __init__(self, flist, filename, key):
         self.flist = flist