Fix non OpenGL CDockWidgets vanish when docking OpenGl widget in the same area

This fix concerns only Windows behaviors

Author: zyrkiel

src/DockWidget.cpp

@@ -376,6 +376,9 @@ CDockWidget::CDockWidget(CDockManager *manager, const QString &title, QWidget* p
 	: QFrame(parent),
 	  d(new DockWidgetPrivate(this))
 {
+	// Force the new CDockWidget to be native so OpenGL widgets are well handled
+	// with non OpenGL widgets
+	winId();
 	d->DockManager = manager;
 	d->Layout = new QBoxLayout(QBoxLayout::TopToBottom);
 	d->Layout->setContentsMargins(0, 0, 0, 0);