Index: Include/unicodeobject.h
===================================================================
--- Include/unicodeobject.h	(Revision 75130)
+++ Include/unicodeobject.h	(Arbeitskopie)
@@ -390,6 +390,8 @@
         Py_UNICODE_ISDIGIT(ch) || \
         Py_UNICODE_ISNUMERIC(ch))
 
+#define Py_UNICODE_ISCASEIGNORABLE(ch) _PyUnicode_IsCaseIgnorable(ch)
+
 #define Py_UNICODE_COPY(target, source, length)				\
 	Py_MEMCPY((target), (source), (length)*sizeof(Py_UNICODE))
 
Index: Objects/unicodeobject.c
===================================================================
--- Objects/unicodeobject.c	(Revision 75130)
+++ Objects/unicodeobject.c	(Arbeitskopie)
@@ -5417,8 +5417,9 @@
             Py_UNICODE_ISUPPER(ch) ||
             Py_UNICODE_ISTITLE(ch))
             previous_is_cased = 1;
-        else
-            previous_is_cased = 0;
+        else if (!Py_UNICODE_ISCASEIGNORABLE(ch)) {
+             previous_is_cased = 0;
+        }
     }
     return 1;
 }
@@ -6855,8 +6856,9 @@
             previous_is_cased = 1;
             cased = 1;
         }
-        else
-            previous_is_cased = 0;
+        else if (!Py_UNICODE_ISCASEIGNORABLE(ch)) {
+             previous_is_cased = 0;
+        }
     }
     return PyBool_FromLong(cased);
 }
Index: Objects/unicodectype.c
===================================================================
--- Objects/unicodectype.c	(Revision 75130)
+++ Objects/unicodectype.c	(Arbeitskopie)
@@ -20,6 +20,7 @@
 #define TITLE_MASK 0x40
 #define UPPER_MASK 0x80
 #define NODELTA_MASK 0x100
+#define CASE_IGNORABLE_MASK 0x200
 
 typedef struct {
     const Py_UNICODE upper;
@@ -652,6 +653,16 @@
     return _PyUnicode_ToNumeric(ch) != -1.0;
 }
 
+/* Returns 1 for Unicode characters having the category 'Mn', 'Me', 'Cf', 'Lm'
+   or 'Sk',  0 otherwise. */
+
+int _PyUnicode_IsCaseIgnorable(Py_UNICODE ch)
+{
+    const _PyUnicode_TypeRecord *ctype = gettyperecord(ch);
+
+    return (ctype->flags & CASE_IGNORABLE_MASK) != 0;
+}
+
 #ifndef WANT_WCTYPE_FUNCTIONS
 
 /* Returns 1 for Unicode characters having the bidirectional type
Index: Tools/unicode/makeunicodedata.py
===================================================================
--- Tools/unicode/makeunicodedata.py	(Revision 75130)
+++ Tools/unicode/makeunicodedata.py	(Arbeitskopie)
@@ -58,6 +58,7 @@
 TITLE_MASK = 0x40
 UPPER_MASK = 0x80
 NODELTA_MASK = 0x100
+CASE_IGNORABLE_MASK = 0x200
 
 def maketables(trace=0):
 
@@ -369,6 +370,26 @@
                 flags |= TITLE_MASK
             if category == "Lu":
                 flags |= UPPER_MASK
+            if (category in ["Mn", "Me", "Cf", "Lm", "Sk"]
+                or unichr(char) in [u':', u'\xb7', u'\u0387', u'\u05f4',
+                    u'\u2027', u'\ufe13', u'\ufe55', u'\uff1a']
+                or unichr(char) in [u"'", u'.', u'\u2018', u'\u2019', u'\u2024',
+                    u'\ufe52', u'\uff07', u'\uff0e']):
+                #  As of Unicode 5.2.0: "C is defined to be case-ignorable if
+                #    Word_Break(C) = MidLetter or MidNumLet, or
+                #    General_Category(C) = Nonspacing_Mark (Mn),
+                #    Enclosing_Mark (Me), Format (Cf), Modifier_Letter (Lm), or
+                #    Modifier_Symbol (Sk)."
+                # See WordBreakProperty.txt for "Word_Break(C)"
+                # TODO Those hardcoded characters above cannot currently be
+                # extracted automatically, as neither DerivedCoreProperties.txt
+                # nor the source file for property
+                # "Word_Break(C) = MidLetter or MidNumLet" are provided here. In
+                # future "CASE_IGNORABLE_MASK" should be set from the property
+                # "Case_Ignorable (CI)" in http://www.unicode.org/\
+                #   Public/5.2.0/ucd/DerivedCoreProperties.txt
+
+                flags |= CASE_IGNORABLE_MASK
             # use delta predictor for upper/lower/title if it fits
             if record[12]:
                 upper = int(record[12], 16)
Index: Lib/test/test_unicode.py
===================================================================
--- Lib/test/test_unicode.py	(Revision 75130)
+++ Lib/test/test_unicode.py	(Arbeitskopie)
@@ -273,6 +273,9 @@
         string_tests.MixinStrUnicodeUserStringTest.test_title(self)
         self.checkequalnofix(True, u'\u1FFc', 'istitle')
         self.checkequalnofix(True, u'Greek \u1FFcitlecases ...', 'istitle')
+        self.checkequalnofix(True, u'H\u0301ngh', 'istitle')
+        self.checkequalnofix(False, u"This Isn'T Right", 'istitle')
+        self.checkequalnofix(True, u"I Pity The 'Foo'.", 'istitle')
 
     def test_isspace(self):
         string_tests.MixinStrUnicodeUserStringTest.test_isspace(self)