1) #8945: Bulk edit dialog still offers tristate choice for custom Yes/No column

2) change sort to not distinguish between None and False when bools are not tristate.
3) make the check of the tristate tweak always check for 'no' instead of not 'yes'. Intent is to make the system more stable if the user enters garbage into the tweak.

src/calibre/gui2/custom_column_widgets.py

@@ -551,7 +551,11 @@ class BulkBool(BulkBase, Bool):
 
     def setup_ui(self, parent):
         self.make_widgets(parent, QComboBox)
-        items = [_('Yes'), _('No'), _('Undefined')]
+        items = [_('Yes'), _('No')]
+        if tweaks['bool_custom_columns_are_tristate'] == 'no':
+            items.append('')
+        else:
+            items.append(_('Undefined'))
         icons = [I('ok.png'), I('list_remove.png'), I('blank.png')]
         self.main_widget.blockSignals(True)
         for icon, text in zip(icons, items):
@@ -560,7 +564,10 @@ class BulkBool(BulkBase, Bool):
 
     def getter(self):
         val = self.main_widget.currentIndex()
-        return {2: None, 1: False, 0: True}[val]
+        if tweaks['bool_custom_columns_are_tristate'] == 'no':
+            return {2: False, 1: False, 0: True}[val]
+        else:
+            return {2: None, 1: False, 0: True}[val]
 
     def setter(self, val):
         val = {None: 2, False: 1, True: 0}[val]
@@ -576,6 +583,14 @@ class BulkBool(BulkBase, Bool):
             val = False
         self.db.set_custom_bulk(book_ids, val, num=self.col_id, notify=notify)
 
+    def a_c_checkbox_changed(self):
+        if not self.ignore_change_signals:
+            if tweaks['bool_custom_columns_are_tristate'] == 'no' and \
+                                    self.main_widget.currentIndex() == 2:
+                self.a_c_checkbox.setChecked(False)
+            else:
+                self.a_c_checkbox.setChecked(True)
+
 class BulkInt(BulkBase):
 
     def setup_ui(self, parent):

src/calibre/gui2/library/models.py

@@ -685,7 +685,7 @@ class BooksModel(QAbstractTableModel): # {{{
                 self.dc[col] = functools.partial(bool_type, idx=idx)
                 self.dc_decorator[col] = functools.partial(
                             bool_type_decorator, idx=idx,
-                            bool_cols_are_tristate=tweaks['bool_custom_columns_are_tristate'] == 'yes')
+                            bool_cols_are_tristate=tweaks['bool_custom_columns_are_tristate'] != 'no')
             elif datatype == 'rating':
                 self.dc[col] = functools.partial(rating_type, idx=idx)
             elif datatype == 'series':

src/calibre/library/caches.py

@@ -528,7 +528,7 @@ class ResultCache(SearchQueryParser): # {{{
                 location[i] = db_col[loc]
 
             # get the tweak here so that the string lookup and compare aren't in the loop
-            bools_are_tristate = tweaks['bool_custom_columns_are_tristate'] == 'yes'
+            bools_are_tristate = tweaks['bool_custom_columns_are_tristate'] != 'no'
 
             for loc in location: # location is now an array of field indices
                 if loc == db_col['authors']:
@@ -812,7 +812,10 @@ class SortKeyGenerator(object):
                 val = self.string_sort_key(val)
 
             elif dt == 'bool':
-                val = {True: 1, False: 2, None: 3}.get(val, 3)
+                if tweaks['bool_custom_columns_are_tristate'] == 'no':
+                    val = {True: 1, False: 2, None: 2}.get(val, 2)
+                else:
+                    val = {True: 1, False: 2, None: 3}.get(val, 3)
 
             yield val