OS X: Workaround for Qt 5 bug that causes the popup menu on the author to author sort button in the edit metadata dialog to not respond if the mouse button if not released once before clicking menu entries. See #1362338 (Copy Author Sort to Author isn't working)

https://bugreports.qt-project.org/browse/QTBUG-41017

src/calibre/gui2/metadata/single.py

@@ -15,6 +15,7 @@ from PyQt5.Qt import (Qt, QVBoxLayout, QHBoxLayout, QWidget, QPushButton,
         QTabWidget, QIcon, QToolButton, QSplitter, QGroupBox, QSpacerItem,
         QSizePolicy, QFrame, QSize, QKeySequence, QMenu, QShortcut)
 
+from calibre.constants import isosx
 from calibre.ebooks.metadata import authors_to_string, string_to_authors
 from calibre.gui2 import ResizableDialog, error_dialog, gprefs, pixmap_to_data
 from calibre.gui2.metadata.basic_widgets import (TitleEdit, AuthorsEdit,
@@ -129,6 +130,17 @@ class MetadataSingleDialogBase(ResizableDialog):
               'change author sort from red to green.  There is a menu of '
               'functions available under this button. Click and hold '
               'on the button to see it.') + '</p>')
+        if isosx:
+            # Workaround for https://bugreports.qt-project.org/browse/QTBUG-41017
+            class Menu(QMenu):
+
+                def mouseReleaseEvent(self, ev):
+                    ac = self.actionAt(ev.pos())
+                    if ac is not None:
+                        ac.trigger()
+                    return QMenu.mouseReleaseEvent(self, ev)
+            b.m = m = Menu()
+        else:
             b.m = m = QMenu()
         ac = m.addAction(QIcon(I('forward.png')), _('Set author sort from author'))
         ac2 = m.addAction(QIcon(I('back.png')), _('Set author from author sort'))