Fix #2034757 [[Enhancement] E-book viewer: search pane should have a …

…context menu](https://bugs.launchpad.net/calibre/+bug/2034757)

src/calibre/gui2/viewer/search.py

@@ -6,8 +6,8 @@
 from collections import Counter, OrderedDict
 from html import escape
 from qt.core import (
-    QAbstractItemView, QCheckBox, QComboBox, QFont, QHBoxLayout, QIcon, QLabel, Qt,
-    QToolButton, QTreeWidget, QTreeWidgetItem, QVBoxLayout, QWidget, pyqtSignal,
+    QAbstractItemView, QCheckBox, QComboBox, QFont, QHBoxLayout, QIcon, QLabel, QMenu,
+    Qt, QToolButton, QTreeWidget, QTreeWidgetItem, QVBoxLayout, QWidget, pyqtSignal,
 )
 from threading import Thread
 
@@ -542,6 +542,8 @@ class Results(QTreeWidget):  # {{{
 
     def __init__(self, parent=None):
         QTreeWidget.__init__(self, parent)
+        self.setContextMenuPolicy(Qt.ContextMenuPolicy.CustomContextMenu)
+        self.customContextMenuRequested.connect(self.show_context_menu)
         self.setHeaderHidden(True)
         self.setFocusPolicy(Qt.FocusPolicy.NoFocus)
         self.delegate = ResultsDelegate(self)
@@ -558,6 +560,14 @@ def __init__(self, parent=None):
         self.gesture_manager = GestureManager(self)
         self.setVerticalScrollMode(QAbstractItemView.ScrollMode.ScrollPerPixel)
 
+    def show_context_menu(self, point):
+        self.context_menu = m = QMenu(self)
+        m.addAction(QIcon.ic('plus.png'), _('Expand all'), self.expandAll)
+        m.addAction(QIcon.ic('minus.png'), _('Collapse all'), self.collapseAll)
+        self.context_menu.popup(self.mapToGlobal(point))
+        return True
+
+
     def viewportEvent(self, ev):
         if hasattr(self, 'gesture_manager'):
             ret = self.gesture_manager.handle_event(ev)