Support Unity's global menu bar for the ebook editor

src/calibre/gui2/main_window.py

@@ -75,6 +75,9 @@ class MainWindow(QMainWindow):
     __actions   = []
 
     keyboard_interrupt = pyqtSignal()
+    # See https://bugreports.qt-project.org/browse/QTBUG-42281
+    window_blocked = pyqtSignal()
+    window_unblocked = pyqtSignal()
 
     @classmethod
     def create_application_menubar(cls):
@@ -129,3 +132,12 @@ class MainWindow(QMainWindow):
             pass
         except:
             pass
+
+    def event(self, ev):
+        # See https://bugreports.qt-project.org/browse/QTBUG-42281
+        etype = ev.type()
+        if etype == ev.WindowBlocked:
+            self.window_blocked.emit()
+        elif etype == ev.WindowUnblocked:
+            self.window_unblocked.emit()
+        return QMainWindow.event(self, ev)

src/calibre/gui2/tweak_book/ui.py

@@ -19,6 +19,7 @@ from PyQt5.Qt import (
 from calibre import prints
 from calibre.constants import __appname__, get_version, isosx, DEBUG
 from calibre.gui2 import elided_text, open_url
+from calibre.gui2.dbus_export.widgets import factory
 from calibre.gui2.keyboard import Manager as KeyboardManager
 from calibre.gui2.main_window import MainWindow
 from calibre.gui2.throbber import ThrobbingButton, create_donate_widget
@@ -461,10 +462,12 @@ class Main(MainWindow):
         create_plugin_actions(actions, toolbar_actions, self.plugin_menu_actions)
 
     def create_menubar(self):
+        if isosx:
             p, q = self.create_application_menubar()
             q.triggered.connect(self.action_quit.trigger)
             p.triggered.connect(self.action_preferences.trigger)
-        b = self.menuBar()
+        f = factory(app_id='com.calibre-ebook.EditBook-%d' % os.getpid())
+        b = f.create_window_menubar(self)
 
         f = b.addMenu(_('&File'))
         f.addAction(self.action_new_file)