Gui: Free NavigationStyle before scenegraph

src/Gui/View3DInventorViewer.cpp

@@ -550,6 +550,8 @@ View3DInventorViewer::~View3DInventorViewer()
     // to prevent following OpenGL error message: "Texture is not valid in the current context. Texture has not been destroyed"
     aboutToDestroyGLContext();
 
+    delete this->navigation;
+
     // It can happen that a document has several MDI views and when the about to be
     // closed 3D view is in edit mode the corresponding view provider must be restored
     // because otherwise it might be left in a broken state
@@ -589,8 +591,6 @@ View3DInventorViewer::~View3DInventorViewer()
     if (this->pcClipPlane)
         this->pcClipPlane->unref();
 
-    delete this->navigation;
-
     // Note: When closing the application the main window doesn't exist any more.
     if (getMainWindow())
         getMainWindow()->setPaneText(2, QLatin1String(""));