MacOS: Disable window controls for windows created by JUCE when a Component is modal

The change does not affect plugin windows, which are created by the
host.

modules/juce_gui_basics/components/juce_ModalComponentManager.cpp

@@ -106,7 +106,10 @@ JUCE_IMPLEMENT_SINGLETON (ModalComponentManager)
 void ModalComponentManager::startModal (Component* component, bool autoDelete)
 {
     if (component != nullptr)
+    {
         stack.add (new ModalItem (component, autoDelete));
+        detail::ComponentHelpers::ModalComponentManagerChangeNotifier::getInstance().modalComponentManagerChanged();
+    }
 }
 
 void ModalComponentManager::attachCallback (Component* component, Callback* callback)
@@ -210,6 +213,8 @@ void ModalComponentManager::handleAsyncUpdate()
                 item->callbacks.getUnchecked (j)->modalStateFinished (item->returnValue);
 
             compToDelete.deleteAndZero();
+
+            detail::ComponentHelpers::ModalComponentManagerChangeNotifier::getInstance().modalComponentManagerChanged();
         }
     }
 }

modules/juce_gui_basics/detail/juce_ComponentHelpers.h

@@ -250,6 +250,31 @@ struct ComponentHelpers
                 if (modalWouldBlockComponent (*c, &modal))
                     (c->*function) (ms, SH::screenPosToLocalPos (*c, ms.getScreenPosition()), Time::getCurrentTime());
     }
+
+    class ModalComponentManagerChangeNotifier
+    {
+    public:
+        static auto& getInstance()
+        {
+            static ModalComponentManagerChangeNotifier instance;
+            return instance;
+        }
+
+        ErasedScopeGuard addListener (std::function<void()> l)
+        {
+            return listeners.addListener (std::move (l));
+        }
+
+        void modalComponentManagerChanged()
+        {
+            listeners.call();
+        }
+
+    private:
+        ModalComponentManagerChangeNotifier() = default;
+
+        detail::CallbackListenerList<> listeners;
+    };
 };
 
 } // namespace juce::detail

modules/juce_gui_basics/native/juce_NSViewComponentPeer_mac.mm

@@ -1712,7 +1712,7 @@ public:
     NSWindow* window = nil;
     NSView* view = nil;
     WeakReference<Component> safeComponent;
-    bool isSharedWindow = false;
+    const bool isSharedWindow = false;
    #if USE_COREGRAPHICS_RENDERING
     bool usingCoreGraphics = true;
    #else
@@ -1998,10 +1998,39 @@ private:
        #endif
     }
 
+    void modalComponentManagerChanged()
+    {
+        if (isSharedWindow)
+            return;
+
+        auto style = [window styleMask];
+
+        if (ModalComponentManager::getInstance()->getNumModalComponents() > 0)
+        {
+            style &= ~NSWindowStyleMaskMiniaturizable;
+            style &= ~NSWindowStyleMaskClosable;
+        }
+        else
+        {
+            const auto flags = getStyleFlags();
+
+            if ((flags & windowHasMinimiseButton) != 0)  style |= NSWindowStyleMaskMiniaturizable;
+            if ((flags & windowHasCloseButton) != 0)     style |= NSWindowStyleMaskClosable;
+        }
+
+        [window setStyleMask: style];
+    }
+
     //==============================================================================
     std::vector<ScopedNotificationCenterObserver> scopedObservers;
     std::vector<ScopedNotificationCenterObserver> windowObservers;
 
+    ErasedScopeGuard modalChangeListenerScope =
+        detail::ComponentHelpers::ModalComponentManagerChangeNotifier::getInstance().addListener ([this]
+                                                                                                  {
+                                                                                                      modalComponentManagerChanged();
+                                                                                                  });
+
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (NSViewComponentPeer)
 };