QShortCut: Check whether the menu is QPA-disabled

When climbing the menu hierarchy, it's sounder to
check whether the actual QPA menu is enabled. This
way we can trigger modifier-less shortcuts even in
submenus.

Task-number: QTBUG-38256
Task-number: QTBUG-42584
Change-Id: I13a27027306bce0f0732b05bf9469f3b77028f73
Reviewed-by: Liang Qi <liang.qi@theqtcompany.com>

src/gui/kernel/qplatformmenu.h

@@ -103,6 +103,7 @@ public:
     virtual void setText(const QString &text) = 0;
     virtual void setIcon(const QIcon &icon) = 0;
     virtual void setEnabled(bool enabled) = 0;
+    virtual bool isEnabled() const { return true; }
     virtual void setVisible(bool visible) = 0;
     virtual void setMinimumWidth(int width) { Q_UNUSED(width); }
     virtual void setFont(const QFont &font) { Q_UNUSED(font); }

src/plugins/platforms/cocoa/qcocoamenu.h

@@ -58,6 +58,7 @@ public:
     void removeMenuItem(QPlatformMenuItem *menuItem);
     void syncMenuItem(QPlatformMenuItem *menuItem);
     void setEnabled(bool enabled);
+    bool isEnabled() const;
     void setVisible(bool visible);
     void showPopup(const QWindow *parentWindow, const QRect &targetRect, const QPlatformMenuItem *item);
     void dismiss();

src/plugins/platforms/cocoa/qcocoamenu.mm

@@ -426,6 +426,11 @@ void QCocoaMenu::setEnabled(bool enabled)
     syncModalState(!m_enabled);
 }
 
+bool QCocoaMenu::isEnabled() const
+{
+    return [m_nativeItem isEnabled];
+}
+
 void QCocoaMenu::setVisible(bool visible)
 {
     [m_nativeItem setSubmenu:(visible ? m_nativeMenu : nil)];

src/widgets/kernel/qshortcut.cpp

@@ -44,6 +44,7 @@
 #include <private/qshortcutmap_p.h>
 #include <private/qaction_p.h>
 #include <private/qwidgetwindow_p.h>
+#include <qpa/qplatformmenu.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -269,9 +270,13 @@ static bool correctActionContext(Qt::ShortcutContext context, QAction *a, QWidge
             // On Mac, menu item shortcuts are processed before reaching any window.
             // That means that if a menu action shortcut has not been already processed
             // (and reaches this point), then the menu item itself has been disabled.
-            // This occurs at the QPA level on Mac, were we disable all the Cocoa menus
-            // when showing a modal window.
-            if (a->shortcut().count() < 1 || (a->shortcut().count() == 1 && (a->shortcut()[0] & Qt::MODIFIER_MASK) != 0))
+            // This occurs at the QPA level on Mac, where we disable all the Cocoa menus
+            // when showing a modal window. (Notice that only the QPA menu is disabled,
+            // not the QMenu.) Since we can also reach this code by climbing the menu
+            // hierarchy (see below), or when the shortcut is not a key-equivalent, we
+            // need to check whether the QPA menu is actually disabled.
+            QPlatformMenu *pm = menu->platformMenu();
+            if (!pm || !pm->isEnabled())
                 continue;
 #endif
             QAction *a = menu->menuAction();