[skip ci] make Jupyter notebook integration working again

src/Main/FreeCADGuiPy.cpp

@@ -120,17 +120,20 @@ FreeCADGui_showMainWindow(PyObject * /*self*/, PyObject *args)
             t.detach();
         }
         else {
+            // In order to get Jupiter notebook integration working we must create a direct instance
+            // of QApplication. Not even a sub-class can be used because otherwise PySide2 wraps it
+            // with a QtCore.QCoreApplication which will raise an exception in ipykernel
 #if defined(Q_OS_WIN)
             static int argc = 0;
             static char **argv = {0};
-            (void)new QtApplication(argc, argv);
+            (void)new QApplication(argc, argv);
             // When QApplication is constructed
             hhook = SetWindowsHookEx(WH_GETMESSAGE,
                 FilterProc, 0, GetCurrentThreadId());
 #elif !defined(QT_NO_GLIB)
             static int argc = 0;
             static char **argv = {0};
-            (void)new QtApplication(argc, argv);
+            (void)new QApplication(argc, argv);
 #else
             PyErr_SetString(PyExc_RuntimeError, "Must construct a QApplication before a QPaintDevice\n");
             return NULL;