Several changes:

1. Improve performance by caching all icons.
2. Use different icons instead of a check mark for notes. Sorting uses the icon.
3. In manage tags, make the edit button on the left work on all editable cells. Correct the tooltip.
4. In manage tags, put the button press shortcut descriptions into the tooltips.
5. In manage authors, add an "Edit cell" button that works with all editable cells.

src/calibre/gui2/dialogs/edit_authors_dialog.py

@@ -15,7 +15,7 @@ from qt.core import (
 from calibre.ebooks.metadata import author_to_author_sort, string_to_authors
 from calibre.gui2 import error_dialog, gprefs
 from calibre.gui2.dialogs.edit_authors_dialog_ui import Ui_EditAuthorsDialog
-from calibre.gui2.dialogs.tag_list_editor import CHECK_MARK, NotesUtilities
+from calibre.gui2.dialogs.tag_list_editor import NotesUtilities, NotesTableWidgetItem
 from calibre.utils.config import prefs
 from calibre.utils.config_base import tweaks
 from calibre.utils.icu import (
@@ -116,6 +116,7 @@ class EditAuthorsDialog(QDialog, Ui_EditAuthorsDialog):
         self.apply_vl_checkbox.toggled.connect(self.use_vl_changed)
         self.apply_selection_checkbox.setContentsMargins(0, 0, 0, 0)
         self.apply_selection_checkbox.toggled.connect(self.apply_selection_box_changed)
+        self.edit_current_cell.clicked.connect(self.edit_cell)
 
         self.table.setAlternatingRowColors(True)
         self.table.setSelectionMode(QAbstractItemView.SelectionMode.SingleSelection)
@@ -205,6 +206,10 @@ class EditAuthorsDialog(QDialog, Ui_EditAuthorsDialog):
                                                       self.notes_utilities, self.get_item_id))
         self.show_table(id_to_select, select_sort, select_link, is_first_letter)
 
+    def edit_cell(self):
+        if self.table.currentIndex().isValid():
+            self.table.editItem(self.table.currentItem())
+
     def get_item_id(self, item):
         return int(self.table.item(item.row(), AUTHOR_COLUMN).data(Qt.ItemDataRole.UserRole))
 
@@ -252,8 +257,6 @@ class EditAuthorsDialog(QDialog, Ui_EditAuthorsDialog):
         row = 0
         from calibre.gui2.ui import get_gui
         all_items_that_have_notes = get_gui().current_db.new_api.get_all_items_that_have_notes('authors')
-        yes, yes_skey = CHECK_MARK, sort_key(CHECK_MARK)
-        no, no_skey = '', sort_key('')
         for id_, v in self.authors.items():
             if id_ not in auts_to_show:
                 continue
@@ -268,16 +271,13 @@ class EditAuthorsDialog(QDialog, Ui_EditAuthorsDialog):
             self.table.setItem(row, AUTHOR_COLUMN, name_item)
             self.table.setItem(row, AUTHOR_SORT_COLUMN, sort_item)
             self.table.setItem(row, LINK_COLUMN, link_item)
-            if id_ in all_items_that_have_notes:
+            note_item = NotesTableWidgetItem()
-                note_item = TableItem(yes, yes_skey)
-            else:
-                note_item = TableItem(no, no_skey)
             self.table.setItem(row, NOTES_COLUMN, note_item)
 
             self.set_icon(name_item, id_)
             self.set_icon(sort_item, id_)
             self.set_icon(link_item, id_)
-            self.set_icon(note_item, id_)
+            self.notes_utilities.set_icon(note_item, id_, id_ in all_items_that_have_notes)
             row += 1
 
         self.table.setHorizontalHeaderLabels([_('Author'), _('Author sort'), _('Link'), _('Notes')])
@@ -569,6 +569,8 @@ class EditAuthorsDialog(QDialog, Ui_EditAuthorsDialog):
             self.table.setFocus(Qt.FocusReason.OtherFocusReason)
 
     def set_icon(self, item, id_):
+        if item.column() == NOTES_COLUMN:
+            raise ValueError('got set_icon on notes column')
         modified = self.item_is_modified(item, id_)
         item.setIcon(self.edited_icon if modified else QIcon())
 
@@ -596,10 +598,10 @@ class EditAuthorsDialog(QDialog, Ui_EditAuthorsDialog):
                 item = c
             else:
                 item  = self.table.item(row, col)
-                item.set_sort_key()
-                self.set_icon(item, id_)
                 name = self.get_column_name(col)
                 if name != 'notes':
+                    item.set_sort_key()
+                    self.set_icon(item, id_)
                     self.authors[id_][self.get_column_name(col)] = str(item.text())
         self.table.setCurrentItem(item)
         self.table.scrollToItem(item)

src/calibre/gui2/dialogs/edit_authors_dialog.ui

@@ -182,7 +182,19 @@ after changing Preferences->Advanced->Tweaks->Author sort name algorith
        </property>
       </widget>
      </item>
-     <item row="1" column="2">
+     <item row="1" column="3">
+      <widget class="QPushButton" name="edit_current_cell">
+       <property name="toolTip">
+        <string>&lt;p&gt;Edit the currently selected cell. If an author is edited then it is renamed
+                in every book where it is used. Double-clicking and pressing the edit
+                key also work.&lt;/p&gt;</string>
+       </property>
+       <property name="text">
+        <string>Edi&amp;t current cell</string>
+       </property>
+      </widget>
+     </item>
+     <item row="1" column="4">
       <widget class="QDialogButtonBox" name="buttonBox">
        <property name="sizePolicy">
         <sizepolicy hsizetype="Minimum" vsizetype="Fixed">

src/calibre/gui2/dialogs/tag_list_editor.py

@@ -33,6 +33,9 @@ CHECK_MARK = '✓'
 
 class NameTableWidgetItem(QTableWidgetItem):
 
+    empty_icon = QIcon()
+    trash_icon = QIcon.ic('trash.png')
+
     def __init__(self, sort_key):
         QTableWidgetItem.__init__(self)
         self.initial_value = ''
@@ -53,9 +56,9 @@ class NameTableWidgetItem(QTableWidgetItem):
 
     def set_is_deleted(self, to_what):
         if to_what:
-            self.setIcon(QIcon.ic('trash.png'))
+            self.setIcon(self.trash_icon)
         else:
-            self.setIcon(QIcon())
+            self.setIcon(self.empty_icon)
             self.current_value = self.initial_value
         self.is_deleted = to_what
 
@@ -116,8 +119,39 @@ class CountTableWidgetItem(QTableWidgetItem):
         return self._count < other._count
 
 
+class NotesTableWidgetItem(QTableWidgetItem):
+
+    # These define the sort order for notes columns
+    EMPTY = 0
+    UNCHANGED = 1
+    EDITED = 2
+    DELETED = 3
+
+    def __init__(self):
+        QTableWidgetItem.__init__(self, '')
+        self.set_sort_val(self.EMPTY)
+
+    def set_sort_val(self, val):
+        self._sort_val = val
+
+    def __ge__(self, other):
+        return self._sort_val >= other._sort_val
+
+    def __lt__(self, other):
+        return self._sort_val < other._sort_val
+
+
 class NotesUtilities():
 
+    edit_icon = QIcon.ic('edit_input.png')
+    edited_icon = QIcon.ic('modified.png')
+    empty_icon = QIcon()
+    export_icon = QIcon.ic('forward.png')
+    import_icon = QIcon.ic('back.png')
+    pencil_icon = QIcon.ic('notes.png')
+    trash_icon = QIcon.ic('trash.png')
+    undo_delete_icon = QIcon.ic('edit-undo.png')
+
     def __init__(self, table, category, item_id_getter):
         self.table = table
         self.modified_notes = {}
@@ -141,9 +175,25 @@ class NotesUtilities():
                 db.set_notes_for(self.category, item_id, '')
         self.modified_notes.clear()
 
-    def change_text(self, item, val):
+    def set_icon(self, item, id_, has_value):
         with block_signals(self.table):
-            item.setText(CHECK_MARK if bool(val) else '')
+            if id_ not in self.modified_notes:
+                if not has_value:
+                    item.setIcon(self.empty_icon)
+                    item.set_sort_val(NotesTableWidgetItem.EMPTY)
+                else:
+                    item.setIcon(self.pencil_icon)
+                    item.set_sort_val(NotesTableWidgetItem.UNCHANGED)
+            else:
+                if has_value:
+                    item.setIcon(self.edited_icon)
+                    item.set_sort_val(NotesTableWidgetItem.EDITED)
+                elif not bool(self.modified_notes[id_]):
+                    item.setIcon(self.empty_icon)
+                    item.set_sort_val(NotesTableWidgetItem.EMPTY)
+                else:
+                    item.setIcon(self.trash_icon)
+                    item.set_sort_val(NotesTableWidgetItem.DELETED)
         self.table.cellChanged.emit(item.row(), item.column())
         self.table.itemChanged.emit(item)
 
@@ -158,7 +208,7 @@ class NotesUtilities():
             after = db.notes_for(self.category, item_id)
             if item_id not in self.modified_notes:
                 self.modified_notes[item_id] = note
-            self.change_text(item, after)
+            self.set_icon(item, item_id, bool(after))
 
     def undo_note_edit(self, item):
         item_id = self.item_id_getter(item)
@@ -169,7 +219,7 @@ class NotesUtilities():
                 db.import_note(self.category, item_id, before.encode('utf-8'), path_is_data=True)
             else:
                 db.set_notes_for(self.category, item_id, '')
-        self.change_text(item, before)
+        self.set_icon(item, item_id, bool(before))
 
     def delete_note(self, item):
         item_id = self.item_id_getter(item)
@@ -177,7 +227,7 @@ class NotesUtilities():
         if item_id not in self.modified_notes:
             self.modified_notes[item_id] = db.notes_for(self.category, item_id)
         db.set_notes_for(self.category, item_id, '')
-        self.change_text(item, False)
+        self.set_icon(item, item_id, False)
 
     def do_export(self, item, item_name):
         item_id = self.item_id_getter(item)
@@ -202,13 +252,7 @@ class NotesUtilities():
                 self.modified_notes[item_id] = before
             db.import_note(self.category, item_id, src[0])
             after = db.notes_for(self.category, item_id)
-            self.change_text(item, after)
+            self.set_icon(item, item_id, bool(after))
-
-    edit_icon = QIcon.ic('edit_input.png')
-    delete_icon = QIcon.ic('trash.png')
-    undo_delete_icon = QIcon.ic('edit-undo.png')
-    export_icon = QIcon.ic('forward.png')
-    import_icon = QIcon.ic('back.png')
 
     def context_menu(self, menu, item, item_name):
         m = menu
@@ -224,7 +268,7 @@ class NotesUtilities():
         ac = m.addAction(self.edit_icon, _('Edit note') if has_note else _('Create note'))
         ac.triggered.connect(partial(self.table.editItem, item))
 
-        ac = m.addAction(self.delete_icon, _('Delete note'))
+        ac = m.addAction(self.trash_icon, _('Delete note'))
         ac.setEnabled(has_note)
         ac.triggered.connect(partial(self.delete_note, item))
 
@@ -297,6 +341,7 @@ def block_signals(widget):
 class TagListEditor(QDialog, Ui_TagListEditor):
 
     edited_icon = QIcon.ic('modified.png')
+    empty_icon = QIcon()
 
     def __init__(self, window, cat_name, tag_to_match, get_book_ids, sorter,
                  ttm_is_first_letter=False, category=None, fm=None, link_map=None):
@@ -348,7 +393,7 @@ class TagListEditor(QDialog, Ui_TagListEditor):
             self.string_contains = self.case_insensitive_compare
 
         self.delete_button.clicked.connect(self.delete_tags)
-        self.rename_button.clicked.connect(self.rename_tag)
+        self.rename_button.clicked.connect(self.edit_button_clicked)
         self.undo_button.clicked.connect(self.undo_edit)
 
         self.buttonBox.button(QDialogButtonBox.StandardButton.Ok).setText(_('&OK'))
@@ -449,7 +494,7 @@ class TagListEditor(QDialog, Ui_TagListEditor):
 
         ca = m.addAction(_('Edit'))
         ca.setIcon(QIcon.ic('edit_input.png'))
-        ca.triggered.connect(self.rename_tag)
+        ca.triggered.connect(self.edit_button_clicked)
         ca.setEnabled(not item.is_deleted)
 
         ca = m.addAction(_('Delete'))
@@ -622,7 +667,7 @@ class TagListEditor(QDialog, Ui_TagListEditor):
         self.table.setItemDelegateForColumn(NOTES_COLUMN, self.edit_delegate)
 
         self.table.delete_pressed.connect(self.delete_pressed)
-        self.table.itemDoubleClicked.connect(self._rename_tag)
+        self.table.itemDoubleClicked.connect(self.edit_item)
         self.table.itemChanged.connect(self.finish_editing)
         self.table.itemSelectionChanged.connect(self.selection_changed)
 
@@ -665,7 +710,7 @@ class TagListEditor(QDialog, Ui_TagListEditor):
             if self.link_is_edited(id_):
                 item.setIcon(self.edited_icon)
             else:
-                item.setIcon(QIcon())
+                item.setIcon(self.empty_icon)
 
     def fill_in_table(self, tags, tag_to_match, ttm_is_first_letter):
         self.create_table()
@@ -757,13 +802,12 @@ class TagListEditor(QDialog, Ui_TagListEditor):
                 self.table.setItem(row, LINK_COLUMN, item)
 
                 if self.supports_notes:
-                    item = QTableWidgetItem()
+                    item = NotesTableWidgetItem()
-                    self.notes_utilities.change_text(item, id_ in all_items_that_have_notes)
+                    self.notes_utilities.set_icon(item, id_, id_ in all_items_that_have_notes)
                     if is_deleted:
                         item.setFlags(item.flags() & ~(Qt.ItemFlag.ItemIsSelectable|Qt.ItemFlag.ItemIsEditable))
                     else:
                         item.setFlags(item.flags() | (Qt.ItemFlag.ItemIsSelectable|Qt.ItemFlag.ItemIsEditable))
-                    item.setIcon(self.edited_icon if id_ in self.notes_utilities.modified_notes else QIcon())
                     self.table.setItem(row, NOTES_COLUMN, item)
 
             # re-sort the table
@@ -851,9 +895,7 @@ class TagListEditor(QDialog, Ui_TagListEditor):
             return
 
         if edited_item.column() == NOTES_COLUMN:
-            id_ = self.get_item_id(edited_item)
+            # Done elsewhere
-            with block_signals(self.table):
-                edited_item.setIcon(self.edited_icon if id_ in self.notes_utilities.modified_notes else QIcon())
             return
 
         # Item value column
@@ -884,7 +926,7 @@ class TagListEditor(QDialog, Ui_TagListEditor):
                     item.setIcon(self.edited_icon)
                     orig.setData(Qt.ItemDataRole.DisplayRole, item.initial_text())
                 else:
-                    item.setIcon(QIcon())
+                    item.setIcon(self.empty_icon)
                     orig.setData(Qt.ItemDataRole.DisplayRole, '')
 
     def undo_link_edit(self, item, item_id):
@@ -896,7 +938,7 @@ class TagListEditor(QDialog, Ui_TagListEditor):
         item = self.table.item(item.row(), LINK_COLUMN)
         item.setFlags(item.flags() | Qt.ItemFlag.ItemIsEditable | Qt.ItemFlag.ItemIsSelectable)
         item.setText(link_txt)
-        item.setIcon(QIcon())
+        item.setIcon(self.empty_icon)
 
     def undo_value_edit(self, item, item_id):
         with block_signals(self.table):
@@ -904,7 +946,7 @@ class TagListEditor(QDialog, Ui_TagListEditor):
             self.to_rename.pop(item_id, None)
             row = item.row()
             self.table.item(row, WAS_COLUMN).setData(Qt.ItemDataRole.DisplayRole, '')
-            item.setIcon(self.edited_icon if item.text_is_modified() else QIcon())
+            item.setIcon(self.edited_icon if item.text_is_modified() else self.empty_icon)
 
     def undo_edit(self):
         col_zero_items = (self.table.item(item.row(), VALUE_COLUMN) for item in self.table.selectedItems())
@@ -934,7 +976,7 @@ class TagListEditor(QDialog, Ui_TagListEditor):
                 item.setFlags(item.flags() | Qt.ItemFlag.ItemIsEditable | Qt.ItemFlag.ItemIsSelectable)
                 if id_ in self.notes_utilities.modified_notes:
                     self.notes_utilities.undo_note_edit(item)
-                    item.setIcon(QIcon())
+                    item.setIcon(self.empty_icon)
 
     def selection_changed(self):
         if self.table.currentIndex().isValid():
@@ -957,13 +999,10 @@ class TagListEditor(QDialog, Ui_TagListEditor):
                 return True
         return False
 
-    def rename_tag(self):
+    def edit_button_clicked(self):
-        if self.table.currentColumn() != VALUE_COLUMN:
+        self.edit_item(self.table.currentItem())
-            return
-        item = self.table.item(self.table.currentRow(), VALUE_COLUMN)
-        self._rename_tag(item)
 
-    def _rename_tag(self, item):
+    def edit_item(self, item):
         if item is None:
             error_dialog(self, _('No item selected'),
                          _('You must select one item from the list of available items.')).exec()

src/calibre/gui2/dialogs/tag_list_editor.ui

@@ -172,7 +172,9 @@
      <item>
       <widget class="QToolButton" name="delete_button">
        <property name="toolTip">
-        <string>Delete selected items from the database. This will unapply the items from all books and then remove them from the database.</string>
+        <string>&lt;p&gt;Delete selected items from the database.
+                This will unapply the items from all books and then remove them
+                from the database. This button's shortcut is Ctrl+D&lt;/p&gt;</string>
        </property>
        <property name="text">
         <string>...</string>
@@ -208,7 +210,9 @@
      <item>
       <widget class="QToolButton" name="rename_button">
        <property name="toolTip">
-        <string>Rename the items in every book where they are used</string>
+        <string>&lt;p&gt;Edit the currently selected cell. If a tag is edited then it is renamed
+                in every book where it is used. Double-clicking and pressing the edit
+                key also work. This button's shortcut is Ctrl+E&lt;/p&gt;</string>
        </property>
        <property name="text">
         <string>...</string>
@@ -224,7 +228,7 @@
         </size>
        </property>
        <property name="shortcut">
-        <string>Ctrl+R</string>
+        <string>Ctrl+E</string>
        </property>
       </widget>
      </item>
@@ -244,7 +248,9 @@
      <item>
       <widget class="QToolButton" name="undo_button">
        <property name="toolTip">
-        <string>Undo any deletes or edits on the selected lines</string>
+        <string>&lt;p&gt;Undo all deletes or edits on the selected lines.
+                This button's shortcut is Ctrl+U&lt;/p&gt;
+        </string>
        </property>
        <property name="text">
         <string>...</string>