More accessibility changes related to the book list header context menu:

1) add a dialog to set the width without using the mouse.
2) Change the name from "Book list context menu" to "Book list header menu" to avoid confusion with the context menu on book list cells.

src/calibre/gui2/actions/booklist_context_menu.py

@@ -9,8 +9,8 @@ from calibre.gui2.actions import InterfaceAction
 class BooklistContextMenuAction(InterfaceAction):
 
     name = 'Booklist context menu'
-    action_spec = (_('Book list context menu'), 'context_menu.png',
-                   _('Show the book list context menu'), '')
+    action_spec = (_('Book list header menu'), 'context_menu.png',
+                   _('Show the book list header context menu'), '')
     action_type = 'current'
     action_add_menu = False
     dont_add_to = frozenset(['context-menu-device', 'menubar-device'])

src/calibre/gui2/library/views.py

@@ -12,7 +12,8 @@ from collections import OrderedDict
 from qt.core import (
     QTableView, Qt, QAbstractItemView, QMenu, pyqtSignal, QFont, QModelIndex,
     QIcon, QItemSelection, QMimeData, QDrag, QStyle, QPoint, QUrl, QHeaderView, QEvent,
-    QStyleOptionHeader, QItemSelectionModel, QSize, QFontMetrics, QApplication)
+    QStyleOptionHeader, QItemSelectionModel, QSize, QFontMetrics, QApplication,
+    QDialog, QGridLayout, QPushButton, QDialogButtonBox, QLabel, QSpinBox)
 
 from calibre.constants import islinux
 from calibre.gui2.dialogs.enum_values_edit import EnumValuesEdit
@@ -33,11 +34,15 @@ from calibre.utils.icu import primary_sort_key
 from polyglot.builtins import iteritems
 
 
-def restrict_column_width(self, col, old_size, new_size):
+def max_permitted_column_width(self, col):
     # arbitrary: scroll bar + header + some
     sw = self.verticalScrollBar().width() if self.verticalScrollBar().isVisible() else 0
     hw = self.verticalHeader().width() if self.verticalHeader().isVisible() else 0
-    max_width = max(200, self.width() - (sw + hw + 10))
+    return max(200, self.width() - (sw + hw + 10))
+
+
+def restrict_column_width(self, col, old_size, new_size):
+    max_width = max_permitted_column_width(self, col)
     if new_size > max_width:
         self.column_header.blockSignals(True)
         self.setColumnWidth(col, max_width)
@@ -203,6 +208,86 @@ class PreserveViewState:  # {{{
 # }}}
 
 
+class AdjustColumnSize(QDialog): # {{{
+
+    def __init__(self, view, column, name):
+        QDialog.__init__(self)
+        self.setWindowTitle(_('Adjust column size of {0}').format(name))
+        self.view = view
+        self.column = column
+        l = QGridLayout()
+        self.setLayout(l)
+
+        original_size = self.original_size = view.horizontalHeader().sectionSize(column)
+        l.addWidget(QLabel(_('Original size:')), 0, 0)
+        l.addWidget(QLabel(_('{0} pixels').format(str(original_size))), 0, 1)
+
+        self.minimum_size = self.view.horizontalHeader().minimumSectionSize()
+        l.addWidget(QLabel(_('Minimum size:')), 1, 0)
+        l.addWidget(QLabel(_('{0} pixels').format(str(self.minimum_size))), 1, 1)
+
+        self.maximum_size = max_permitted_column_width(self.view, self.column)
+        l.addWidget(QLabel(_('Maximum size:')), 2, 0)
+        l.addWidget(QLabel(_('{0} pixels').format(str(self.maximum_size))), 2, 1)
+
+        b = self.shrink_button = QPushButton('&Shrink 10%')
+        l.addWidget(b, 5, 0)
+        b = self.expand_button = QPushButton('&Expand 10%')
+        l.addWidget(b, 5, 1)
+
+        b = self.set_minimum_button = QPushButton('Set to mi&nimum')
+        l.addWidget(b, 6, 0)
+        b = self.set_maximum_button = QPushButton('Set to ma&ximum')
+        l.addWidget(b, 6, 1)
+
+        sb = self.spin_box = QSpinBox()
+        sb.setMinimum(self.view.horizontalHeader().minimumSectionSize())
+        sb.setMaximum(self.maximum_size)
+        sb.setValue(original_size)
+        sb.setSuffix(' ' + _('pixels'))
+        l.addWidget(sb, 7, 1)
+        sb_label = QLabel('Set &to')
+        l.addWidget(sb_label, 7, 0)
+        sb_label.setBuddy(sb)
+
+        bb = self.button_box = QDialogButtonBox(QDialogButtonBox.StandardButton.Ok |
+                                                QDialogButtonBox.StandardButton.Cancel)
+        l.addWidget(bb, 10, 0, 1, 2)
+
+        self.shrink_button.clicked.connect(self.shrink_button_clicked)
+        self.expand_button.clicked.connect(self.expand_button_clicked)
+        self.spin_box.valueChanged.connect(self.spin_box_changed)
+        self.set_minimum_button.clicked.connect(self.set_minimum_button_clicked)
+        self.set_maximum_button.clicked.connect(self.set_maximum_button_clicked)
+        bb.accepted.connect(self.accept)
+        bb.rejected.connect(self.reject)
+
+    def reject(self):
+        self.view.setColumnWidth(self.column, self.original_size)
+        QDialog.reject(self)
+
+    def set_maximum_button_clicked(self):
+        # Do this dance in case the current width exceeds the maximum, which can
+        # happen if the user is playing across multiple monitors
+        self.spin_box.setValue(self.maximum_size-1)
+        self.spin_box.setValue(self.maximum_size)
+
+    def set_minimum_button_clicked(self):
+        self.spin_box.setValue(self.minimum_size)
+
+    def shrink_button_clicked(self):
+        w = int(self.view.horizontalHeader().sectionSize(self.column) * 0.9)
+        self.spin_box.setValue(w)
+
+    def expand_button_clicked(self):
+        w = int(self.view.horizontalHeader().sectionSize(self.column) * 1.1)
+        self.spin_box.setValue(w)
+
+    def spin_box_changed(self, val):
+        self.view.setColumnWidth(self.column, val)
+# }}}
+
+
 @setup_dnd_interface
 class BooksView(QTableView):  # {{{
 
@@ -508,6 +593,8 @@ class BooksView(QTableView):  # {{{
                 partial(self.resize_column_to_fit, view, col))
         ans.addAction(_('Resize column to fit contents'),
                 partial(self.fit_column_to_contents, view, col))
+        ans.addAction(_('Manually adjust column size'),
+                partial(self.manually_adjust_column_size, view, col, name))
         ans.addAction(_('Restore default layout'), partial(handler, action='defaults'))
         if self.can_add_columns:
             ans.addAction(
@@ -940,6 +1027,10 @@ class BooksView(QTableView):  # {{{
         col = self.column_map.index(column)
         view.resizeColumnToContents(col)
 
+    def manually_adjust_column_size(self, view, column, name):
+        col = self.column_map.index(column)
+        AdjustColumnSize(view, col, name).exec_()
+
     def column_resized(self, col, old_size, new_size):
         restrict_column_width(self, col, old_size, new_size)