diff -r 10efb1797e7b Lib/idlelib/ClassBrowser.py
--- a/Lib/idlelib/ClassBrowser.py	Thu Oct 01 13:16:43 2015 +0200
+++ b/Lib/idlelib/ClassBrowser.py	Mon Oct 05 17:20:54 2015 -0700
@@ -56,7 +56,7 @@
         self.settitle()
         top.focus_set()
         # create scrolled canvas
-        theme = idleConf.GetOption('main','Theme','name')
+        theme = idleConf.CurrentTheme()
         background = idleConf.GetHighlight(theme, 'normal')['background']
         sc = ScrolledCanvas(top, bg=background, highlightthickness=0, takefocus=1)
         sc.frame.pack(expand=1, fill="both")
diff -r 10efb1797e7b Lib/idlelib/ColorDelegator.py
--- a/Lib/idlelib/ColorDelegator.py	Thu Oct 01 13:16:43 2015 +0200
+++ b/Lib/idlelib/ColorDelegator.py	Mon Oct 05 17:20:54 2015 -0700
@@ -60,7 +60,7 @@
         self.tag_raise('sel')
 
     def LoadTagDefs(self):
-        theme = idleConf.GetOption('main','Theme','name')
+        theme = idleConf.CurrentTheme()
         self.tagdefs = {
             "COMMENT": idleConf.GetHighlight(theme, "comment"),
             "KEYWORD": idleConf.GetHighlight(theme, "keyword"),
diff -r 10efb1797e7b Lib/idlelib/EditorWindow.py
--- a/Lib/idlelib/EditorWindow.py	Thu Oct 01 13:16:43 2015 +0200
+++ b/Lib/idlelib/EditorWindow.py	Mon Oct 05 17:20:54 2015 -0700
@@ -745,7 +745,7 @@
         # Called from self.filename_change_hook and from configDialog.py
         self._rmcolorizer()
         self._addcolorizer()
-        theme = idleConf.GetOption('main','Theme','name')
+        theme = idleConf.CurrentTheme()
         normal_colors = idleConf.GetHighlight(theme, 'normal')
         cursor_color = idleConf.GetHighlight(theme, 'cursor', fgBg='fg')
         select_colors = idleConf.GetHighlight(theme, 'hilite')
diff -r 10efb1797e7b Lib/idlelib/PyShell.py
--- a/Lib/idlelib/PyShell.py	Thu Oct 01 13:16:43 2015 +0200
+++ b/Lib/idlelib/PyShell.py	Mon Oct 05 17:20:54 2015 -0700
@@ -152,7 +152,7 @@
             # possible due to update in restore_file_breaks
             return
         if color:
-            theme = idleConf.GetOption('main','Theme','name')
+            theme = idleConf.CurrentTheme()
             cfg = idleConf.GetHighlight(theme, "break")
         else:
             cfg = {'foreground': '', 'background': ''}
@@ -338,7 +338,7 @@
 
     def LoadTagDefs(self):
         ColorDelegator.LoadTagDefs(self)
-        theme = idleConf.GetOption('main','Theme','name')
+        theme = idleConf.CurrentTheme()
         self.tagdefs.update({
             "stdin": {'background':None,'foreground':None},
             "stdout": idleConf.GetHighlight(theme, "stdout"),
@@ -621,7 +621,7 @@
         item = RemoteObjectBrowser.StubObjectTreeItem(self.rpcclt, oid)
         from idlelib.TreeWidget import ScrolledCanvas, TreeNode
         top = Toplevel(self.tkconsole.root)
-        theme = idleConf.GetOption('main','Theme','name')
+        theme = idleConf.CurrentTheme()
         background = idleConf.GetHighlight(theme, 'normal')['background']
         sc = ScrolledCanvas(top, bg=background, highlightthickness=0)
         sc.frame.pack(expand=1, fill="both")
diff -r 10efb1797e7b Lib/idlelib/TreeWidget.py
--- a/Lib/idlelib/TreeWidget.py	Thu Oct 01 13:16:43 2015 +0200
+++ b/Lib/idlelib/TreeWidget.py	Mon Oct 05 17:20:54 2015 -0700
@@ -249,7 +249,7 @@
         except AttributeError:
             # padding carefully selected (on Windows) to match Entry widget:
             self.label = Label(self.canvas, text=text, bd=0, padx=2, pady=2)
-        theme = idleConf.GetOption('main','Theme','name')
+        theme = idleConf.CurrentTheme()
         if self.selected:
             self.label.configure(idleConf.GetHighlight(theme, 'hilite'))
         else:
diff -r 10efb1797e7b Lib/idlelib/configHandler.py
--- a/Lib/idlelib/configHandler.py	Thu Oct 01 13:16:43 2015 +0200
+++ b/Lib/idlelib/configHandler.py	Mon Oct 05 17:20:54 2015 -0700
@@ -373,7 +373,11 @@
 
     def CurrentTheme(self):
         "Return the name of the currently active theme."
-        return self.GetOption('main', 'Theme', 'name', default='')
+        theme = self.GetOption('main', 'Theme', 'name', default='')
+        if self.defaultCfg['highlight'].has_section(theme) or \
+                        self.userCfg['highlight'].has_section(theme):
+            return theme
+        return "IDLE Classic"
 
     def CurrentKeys(self):
         "Return the name of the currently active key set."