Fix embed external ui closing too early

Signed-off-by: falkTX <falktx@falktx.com>

distrho/extra/ExternalWindow.hpp

@@ -79,10 +79,7 @@ public:
 
     virtual bool isQuitting() const
     {
-        if (ext.inUse)
-            return ext.isQuitting;
-
-        return !isVisible();
+        return ext.inUse ? ext.isQuitting : pData.isQuitting;
     }
 
    /**
@@ -90,6 +87,7 @@ public:
     */
     virtual void close()
     {
+        pData.isQuitting = true;
         hide();
 
         if (ext.inUse)
@@ -436,6 +434,7 @@ private:
         uint height;
         double scaleFactor;
         String title;
+        bool isQuitting;
         bool visible;
 
         PrivateData()
@@ -445,6 +444,7 @@ private:
               height(1),
               scaleFactor(1.0),
               title(),
+              isQuitting(false),
               visible(false) {}
     } pData;
 

examples/EmbedExternalUI/EmbedExternalExampleUI.cpp

@@ -125,6 +125,16 @@ protected:
    /* --------------------------------------------------------------------------------------------------------
     * External Window overrides */
 
+    uintptr_t getNativeWindowHandle() const noexcept override
+    {
+#if defined(DISTRHO_OS_MAC)
+#elif defined(DISTRHO_OS_WINDOWS)
+#else
+        return (uintptr_t)fWindow;
+#endif
+        return 0;
+    }
+
     void titleChanged(const char* const title) override
     {
         d_stdout("visibilityChanged %s", title);