diff -r d3c67e2fc68c Lib/idlelib/EditorWindow.py
--- a/Lib/idlelib/EditorWindow.py	Thu Apr 11 19:16:44 2013 -0500
+++ b/Lib/idlelib/EditorWindow.py	Fri Apr 12 00:28:42 2013 -0500
@@ -341,6 +341,36 @@
         self.askinteger = tkSimpleDialog.askinteger
         self.showerror = tkMessageBox.showerror
 
+        self._highlight_workaround()  # Fix selection tags on Windows
+
+    def _highlight_workaround(self):
+        # On Windows, Tk removes painting of the selection
+        # tags which is different behavior than on Linux and Mac.
+        # See issue14146 for more information.
+        if not sys.platform.startswith('win'):
+            return
+
+        text = self.text
+        text.event_add("<<Highlight-FocusOut>>", "<FocusOut>")
+        text.event_add("<<Highlight-FocusIn>>", "<FocusIn>")
+        def highlight_fix(focus):
+            sel_range = text.tag_ranges("sel")
+            if sel_range:
+                if focus == 'out':
+                    HILITE_CONFIG = idleConf.GetHighlight(
+                            idleConf.CurrentTheme(), 'hilite')
+                    text.tag_config("sel_fix", HILITE_CONFIG)
+                    text.tag_raise("sel_fix")
+                    text.tag_add("sel_fix", *sel_range)
+                elif focus == 'in':
+                    text.tag_remove("sel_fix", "1.0", "end")
+
+        text.bind("<<Highlight-FocusOut>>",
+                lambda ev: highlight_fix("out"))
+        text.bind("<<Highlight-FocusIn>>",
+                lambda ev: highlight_fix("in"))
+
+
     def _filename_to_unicode(self, filename):
         """convert filename to unicode in order to display it in Tk"""
         if isinstance(filename, str) or not filename: