Deprecate qt_mac_set_show_menubar for a public cross-platform API.

I'm tired of these "hidden" functions. We have an
AA_MacPluginApplication, but sometimes you may have a legitimate reason
for setting this outside of "plugin applications." In the footsteps of
the menu icon attribute, the attribute is the main leader, but menubars
can disable/enable this locally the new QMenuBar::setNativeMenuBar()
property. Otherwise, the menubars take their que from the application
attribute.

This also works for Windows CE. So, there is a bit on convergence as
well.

Task-number: 236757

2 files changed, 15 insertions, 0 deletions

diff --git a/src/corelib/global/qnamespace.h b/src/corelib/global/qnamespace.h
index 9b26ef3..4873b17 100644
--- a/src/corelib/global/qnamespace.h
+++ b/src/corelib/global/qnamespace.h
@@ -503,6 +503,7 @@ public:
         AA_NativeWindows = 3,
         AA_DontCreateNativeWidgetSiblings = 4,
         AA_MacPluginApplication = 5,
+        AA_DontUseNativeMenuBar = 6,
 
         // Add new attributes before this line
         AA_AttributeCount
diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index e4bd664..c21cf87 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -556,6 +556,20 @@ void QCoreApplication::setAttribute(Qt::ApplicationAttribute attribute, bool on)
         QCoreApplicationPrivate::attribs |= 1 << attribute;
     else
         QCoreApplicationPrivate::attribs &= ~(1 << attribute);
+#ifdef Q_OS_MAC
+    // Turn on the no native menubar here, since we used to
+    // do this implicitly. We DO NOT flip it off if someone sets
+    // it to false.
+    // Ideally, we'd have magic that would be something along the lines of
+    // "follow MacPluginApplication" unless explicitly set.
+    // Considering this attribute isn't only at the beginning
+    // it's unlikely it will ever be a problem, but I want
+    // to have the behavior documented here.
+    if (attribute == Qt::AA_MacPluginApplication && on
+          && !testAttribute(Qt::AA_DontUseNativeMenuBar)) {
+        setAttribute(Qt::AA_DontUseNativeMenuBar, true);
+    }
+#endif
 }
 
 /*!