Add ExternalWindow::isEmbed()

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

distrho/extra/ExternalWindow.hpp

@@ -114,6 +114,14 @@ public:
     }
 
 #if DISTRHO_PLUGIN_HAS_EMBED_UI
+   /**
+      Whether this Window is embed into another (usually not DGL-controlled) Window.
+    */
+    bool isEmbed() const noexcept
+    {
+        return pData.parentWindowHandle != 0;
+    }
+
    /**
       Get the "native" window handle.
       This can be reimplemented in order to pass the child window to hosts that can use such informaton.

examples/EmbedExternalUI/EmbedExternalExampleUI.cpp

@@ -57,7 +57,7 @@ public:
 
         const int screen = DefaultScreen(fDisplay);
         const ::Window root   = RootWindow(fDisplay, screen);
-        const ::Window parent = getParentWindowHandle() != 0 ? (::Window)getParentWindowHandle() : root;
+        const ::Window parent = isEmbed() ? (::Window)getParentWindowHandle() : root;
 
         XSetWindowAttributes attr = {};
         attr.event_mask = KeyPressMask|KeyReleaseMask;