diff -r 5b5ef012cd4e Lib/tkinter/__init__.py
--- a/Lib/tkinter/__init__.py	Thu Aug 22 17:53:06 2013 +0300
+++ b/Lib/tkinter/__init__.py	Fri Aug 23 09:44:02 2013 +0300
@@ -1352,7 +1352,7 @@
                 value = words[i+1]
                 if not value:
                     value = None
-                elif '.' in str(value):
+                elif '.' in value:
                     value = getdouble(value)
                 else:
                     value = getint(value)
@@ -1921,7 +1921,7 @@
         for i in range(0, len(words), 2):
             key = words[i][1:]
             value = words[i+1]
-            if str(value)[:1] == '.':
+            if value[:1] == '.':
                 value = self._nametowidget(value)
             dict[key] = value
         return dict
@@ -1972,7 +1972,7 @@
         for i in range(0, len(words), 2):
             key = words[i][1:]
             value = words[i+1]
-            if str(value)[:1] == '.':
+            if value[:1] == '.':
                 value = self._nametowidget(value)
             dict[key] = value
         return dict
@@ -2021,7 +2021,7 @@
         for i in range(0, len(words), 2):
             key = words[i][1:]
             value = words[i+1]
-            if str(value)[:1] == '.':
+            if value[:1] == '.':
                 value = self._nametowidget(value)
             dict[key] = value
         return dict
diff -r 5b5ef012cd4e Lib/tkinter/test/test_ttk/test_widgets.py
--- a/Lib/tkinter/test/test_ttk/test_widgets.py	Thu Aug 22 17:53:06 2013 +0300
+++ b/Lib/tkinter/test/test_ttk/test_widgets.py	Fri Aug 23 09:44:02 2013 +0300
@@ -105,7 +105,7 @@
 
         cbtn['command'] = ''
         res = cbtn.invoke()
-        self.assertEqual(str(res), '')
+        self.assertEqual(res, '')
         self.assertFalse(len(success) > 1)
         self.assertEqual(cbtn['offvalue'],
             cbtn.tk.globalgetvar(cbtn['variable']))
@@ -453,7 +453,7 @@
 
         cbtn2['command'] = ''
         res = cbtn2.invoke()
-        self.assertEqual(str(res), '')
+        self.assertEqual(res, '')
         self.assertFalse(len(success) > 1)
         self.assertEqual(cbtn2['value'], myvar.get())
         self.assertEqual(myvar.get(),
diff -r 5b5ef012cd4e Misc/NEWS
--- a/Misc/NEWS	Thu Aug 22 17:53:06 2013 +0300
+++ b/Misc/NEWS	Fri Aug 23 09:44:02 2013 +0300
@@ -38,8 +38,6 @@
 Library
 -------
 
-- Issue #16809: Fixed some tkinter incompabilities with Tcl/Tk 8.6.
-
 - Issue #16809: Tkinter's splitlist() and split() methods now accept Tcl_Obj
   argument.
 
diff -r 5b5ef012cd4e Modules/_tkinter.c
--- a/Modules/_tkinter.c	Thu Aug 22 17:53:06 2013 +0300
+++ b/Modules/_tkinter.c	Fri Aug 23 09:44:02 2013 +0300
@@ -263,6 +263,7 @@
     Tcl_ObjType *ListType;
     Tcl_ObjType *ProcBodyType;
     Tcl_ObjType *StringType;
+    Tcl_ObjType *WindowType;
 } TkappObject;
 
 #define Tkapp_Interp(v) (((TkappObject *) (v))->interp)
@@ -551,6 +552,7 @@
     v->ListType = Tcl_GetObjType("list");
     v->ProcBodyType = Tcl_GetObjType("procbody");
     v->StringType = Tcl_GetObjType("string");
+    v->WindowType = Tcl_GetObjType("window");
 
     /* Delete the 'exit' command, which can screw things up */
     Tcl_DeleteCommand(v->interp, "exit");
@@ -1007,6 +1009,12 @@
 #endif
     }
 
+    if (value->typePtr == app->WindowType) {
+        return PyUnicode_FromKindAndData(
+            sizeof(Tcl_UniChar), Tcl_GetUnicode(value),
+            Tcl_GetCharLength(value));
+    }
+
     return newPyTclObject(value);
 }
 
diff -r 5b5ef012cd4e Python/pythonrun.c
--- a/Python/pythonrun.c	Thu Aug 22 17:53:06 2013 +0300
+++ b/Python/pythonrun.c	Fri Aug 23 09:44:02 2013 +0300
@@ -1052,7 +1052,7 @@
     PyObject *std = NULL;
     int status = 0, fd;
     PyObject * encoding_attr;
-    char *encoding = NULL, *errors;
+    char *pythonioencoding = NULL, *encoding, *errors;
 
     /* Hack to avoid a nasty recursion issue when Python is invoked
        in verbose mode: pre-import the Latin-1 and UTF-8 codecs */
@@ -1084,19 +1084,21 @@
     }
     Py_DECREF(wrapper);
 
-    encoding = Py_GETENV("PYTHONIOENCODING");
-    errors = NULL;
-    if (encoding) {
-        encoding = _PyMem_Strdup(encoding);
-        if (encoding == NULL) {
+    pythonioencoding = Py_GETENV("PYTHONIOENCODING");
+    encoding = errors = NULL;
+    if (pythonioencoding) {
+        pythonioencoding = _PyMem_Strdup(pythonioencoding);
+        if (pythonioencoding == NULL) {
             PyErr_NoMemory();
             goto error;
         }
-        errors = strchr(encoding, ':');
+        errors = strchr(pythonioencoding, ':');
         if (errors) {
             *errors = '\0';
             errors++;
         }
+        if (*pythonioencoding)
+            encoding = pythonioencoding;
     }
 
     /* Set sys.stdin */
@@ -1176,7 +1178,7 @@
         status = -1;
     }
 
-    PyMem_Free(encoding);
+    PyMem_Free(pythonioencoding);
     Py_XDECREF(bimod);
     Py_XDECREF(iomod);
     return status;