DBus menu: Implement visibility and automatically hide the menu when the window is blocked by a modal dialog

src/calibre/gui2/dbus_export/demo.py

@@ -10,7 +10,7 @@ import time
 
 from PyQt5.Qt import (
     QApplication, QMainWindow, QVBoxLayout, Qt, QKeySequence, QAction,
-    QActionGroup, QMenu, QPushButton, QWidget, QTimer)
+    QActionGroup, QMenu, QPushButton, QWidget, QTimer, QMessageBox, pyqtSignal)
 
 from calibre.gui2.dbus_export.utils import setup_for_cli_run
 from calibre.gui2.dbus_export.widgets import factory
@@ -22,6 +22,9 @@ def make_checkable(ac, checked=True):
 
 class MainWindow(QMainWindow):
 
+    window_blocked = pyqtSignal()
+    window_unblocked = pyqtSignal()
+
     def __init__(self):
         QMainWindow.__init__(self)
         f = factory()
@@ -84,6 +87,8 @@ class MainWindow(QMainWindow):
         b.clicked.connect(self.add_menu), l.addWidget(b)
         self.rb = b = QPushButton('Remove a created menu')
         b.clicked.connect(self.remove_menu), l.addWidget(b)
+        self.sd = b = QPushButton('Show modal dialog')
+        b.clicked.connect(self.show_dialog), l.addWidget(b)
         print ('DBUS connection unique name:', f.bus.get_unique_name())
 
     def update_tooltip(self):
@@ -143,6 +148,17 @@ class MainWindow(QMainWindow):
     def about_to_show_two(self):
         self.menu_two.addAction('Action added by about to show')
 
+    def show_dialog(self):
+        QMessageBox.information(self, 'A test dialog', 'While this dialog is shown, the global menu should be hidden')
+
+    def event(self, ev):
+        if ev.type() in (ev.WindowBlocked, ev.WindowUnblocked):
+            if ev.type() == ev.WindowBlocked:
+                self.window_blocked.emit()
+            else:
+                self.window_unblocked.emit()
+        return QMainWindow.event(self, ev)
+
 app=QApplication([])
 app.setAttribute(Qt.AA_DontUseNativeMenuBar, False)
 app.setApplicationName('com.calibre-ebook.DBusExportDemo')

src/calibre/gui2/dbus_export/menu.py

@@ -34,7 +34,7 @@ def create_properties_for_action(ac, previous=None):
         ans['label'] = swap_mnemonic_char(text)
     if not ac.isEnabled():
         ans['enabled'] = False
-    if not ac.isVisible():
+    if not ac.isVisible() or ac.property('blocked') is True:
         ans['visible'] = False
     if ac.menu() is not None:
         ans['children-display'] = 'submenu'
@@ -124,6 +124,22 @@ class DBusMenu(QObject):
             self.add_action(ac)
         self.dbus_api.LayoutUpdated(self.dbus_api.revision, 0)
 
+    def set_visible(self, visible):
+        ac = self.id_to_action(0)
+        if ac is not None and self.qmenu is not None:
+            changed = False
+            blocked = not visible
+            for ac in ac.menu().actions():
+                ac_id = self.action_to_id(ac)
+                if ac_id is not None:
+                    old = ac.property('blocked')
+                    if old is not blocked:
+                        ac.setProperty('blocked', blocked)
+                        self.action_changes.add(ac_id)
+                        changed = True
+            if changed:
+                self.action_changed_timer.start()
+
     def add_action(self, ac):
         ac_id = 0 if ac.menu() is self.qmenu else self.next_id
         self._id_to_action[ac_id] = ac

src/calibre/gui2/dbus_export/widgets.py

@@ -37,6 +37,8 @@ class ExportedMenuBar(QMenuBar):
         global menu_counter
         if not parent.isWindow():
             raise ValueError('You must supply a top level window widget as the parent for an exported menu bar')
+        self._blocked = False
+        self.is_visible = True
         QMenuBar.__init__(self, parent)
         QMenuBar.setVisible(self, False)
         self.menu_action = MenuBarAction(self)
@@ -51,6 +53,10 @@ class ExportedMenuBar(QMenuBar):
         self.dbus_menu.publish_new_menu(self)
         self.register()
         parent.installEventFilter(self)
+        # See https://bugreports.qt-project.org/browse/QTBUG-42281
+        if hasattr(parent, 'window_blocked'):
+            parent.window_blocked.connect(self._block)
+            parent.window_unblocked.connect(self._unblock)
 
     def register(self):
         wid = self.parent().effectiveWinId()
@@ -66,16 +72,38 @@ class ExportedMenuBar(QMenuBar):
             self.bus.call_blocking(*args)
 
     def setVisible(self, visible):
-        pass  # no-op
+        self.is_visible = visible
+        self.dbus_menu.set_visible(self.is_visible and not self._blocked)
 
     def isVisible(self):
-        return True
+        return self.is_visible
+
+    def show(self):
+        self.setVisible(True)
+
+    def hide(self):
+        self.setVisible(False)
 
     def menuAction(self):
         return self.menu_action
 
+    def _block(self):
+        self._blocked = True
+        self.setVisible(self.is_visible)
+
+    def _unblock(self):
+        self._blocked = False
+        self.setVisible(self.is_visible)
+
     def eventFilter(self, obj, ev):
         etype = ev.type()
+        # WindowBlocked and WindowUnblocked aren't delivered to event filters,
+        # so we have to rely on co-operation from the mainwindow class
+        # See https://bugreports.qt-project.org/browse/QTBUG-42281
+        # if etype == QEvent.WindowBlocked:
+        #     self._block()
+        # elif etype == QEvent.WindowUnblocked:
+        #     self._unblock()
         if etype == QEvent.WinIdChange:
             self.unregister()
             self.register()