wxWakeUpIdle when render timer ends to ensure idle function spawns and triggers rendering

src/slic3r/GUI/GLCanvas3D.cpp

@@ -2996,6 +2996,7 @@ void GLCanvas3D::on_render_timer(wxTimerEvent& evt)
     }
     //render();
     m_dirty = true;
+    wxWakeUpIdle();
 }
 
 void GLCanvas3D::request_extra_frame_delayed(int miliseconds)

src/slic3r/GUI/NotificationManager.cpp

@@ -1444,7 +1444,7 @@ void NotificationManager::update_notifications()
 	}
 
 	if (next_render == 0)
-		wxGetApp().plater()->get_current_canvas3D()->request_extra_frame();
+		wxGetApp().plater()->get_current_canvas3D()->request_extra_framee_delayed(33); //few milliseconds to get from GLCanvas::render
 	else if (next_render < max)
 		wxGetApp().plater()->get_current_canvas3D()->request_extra_frame_delayed(int(next_render));