1 files changed, 37 insertions, 0 deletions
diff --git a/src/plugins/platforms/cocoa/qcocoaintegration.mm b/src/plugins/platforms/cocoa/qcocoaintegration.mm
index dd17848109..55b3805df3 100644
--- a/src/plugins/platforms/cocoa/qcocoaintegration.mm
+++ b/src/plugins/platforms/cocoa/qcocoaintegration.mm
@@ -179,6 +179,9 @@ QCocoaIntegration::QCocoaIntegration(const QStringList &paramList)
     QMacInternalPasteboardMime::initializeMimeTypes();
     QCocoaMimeTypes::initializeMimeTypes();
     QWindowSystemInterfacePrivate::TabletEvent::setPlatformSynthesizesMouse(false);
+
+    connect(qGuiApp, &QGuiApplication::focusWindowChanged,
+        this, &QCocoaIntegration::focusWindowChanged);
 }
 
 QCocoaIntegration::~QCocoaIntegration()
@@ -222,6 +225,8 @@ QCocoaIntegration::Options QCocoaIntegration::options() const
     return mOptions;
 }
 
+Q_LOGGING_CATEGORY(lcCocoaScreen, "qt.qpa.cocoa.screens");
+
 /*!
     \brief Synchronizes the screen list, adds new screens, removes deleted ones
 */
@@ -261,9 +266,11 @@ void QCocoaIntegration::updateScreens()
         if (screen) {
             remainingScreens.remove(screen);
             screen->updateGeometry();
+            qCDebug(lcCocoaScreen) << "Updated properties of" << screen;
         } else {
             screen = new QCocoaScreen(i);
             mScreens.append(screen);
+            qCDebug(lcCocoaScreen) << "Adding" << screen;
             screenAdded(screen);
         }
         siblings << screen;
@@ -280,6 +287,7 @@ void QCocoaIntegration::updateScreens()
         mScreens.removeOne(screen);
         // Prevent stale references to NSScreen during destroy
         screen->m_screenIndex = -1;
+        qCDebug(lcCocoaScreen) << "Removing" << screen;
         destroyScreen(screen);
     }
 }
@@ -505,4 +513,33 @@ void QCocoaIntegration::beep() const
     NSBeep();
 }
 
+void QCocoaIntegration::focusWindowChanged(QWindow *focusWindow)
+{
+    // Don't revert icon just because we lost focus
+    if (!focusWindow)
+        return;
+
+    static bool hasDefaultApplicationIcon = [](){
+        NSImage *genericApplicationIcon = [[NSWorkspace sharedWorkspace]
+            iconForFileType:NSFileTypeForHFSTypeCode(kGenericApplicationIcon)];
+        NSImage *applicationIcon = [NSImage imageNamed:NSImageNameApplicationIcon];
+
+        NSRect rect = NSMakeRect(0, 0, 32, 32);
+        return [applicationIcon CGImageForProposedRect:&rect context:nil hints:nil]
+            == [genericApplicationIcon CGImageForProposedRect:&rect context:nil hints:nil];
+    }();
+
+    // Don't let the window icon override an explicit application icon set in the Info.plist
+    if (!hasDefaultApplicationIcon)
+        return;
+
+    // Or an explicit application icon set on QGuiApplication
+    if (!qGuiApp->windowIcon().isNull())
+        return;
+
+    setApplicationIcon(focusWindow->icon());
+}
+
+#include "moc_qcocoaintegration.cpp"
+
 QT_END_NAMESPACE