Please refer to the project "Editor" which is located in the SeeDraw Samples folder.
// Render background object.
// Move the current vertex to other position.
m_object.SetWindowVertex(curnodeIdx, new SeeDraw.sdGeometry.Point2D(e.X, e.Y));
// Redraw the object
// Update all the entities that Drawn by DrawEntity to the screen.
Fast refresh can only be used in the condition that the
background is a static drawing !!!