Can someone please clear my confusion about the major function calls related to WM_PAINT and the sequence in which they are called. I want to know when these functions: OnUpdate OnInitialUpdate UpdateAllViews OnDraw InvalidateRect are called - whether before or after WM_PAINT, and in what sequence. I've read that InvalidatRect just adds the rectangle to the update region, but it seems to me that a call to it also causes the window to be repainted immediately, or in ther words, a WM_PAINT is passed. Is that true? It would be great if someone can explain me the MFC drawing sequence and procedure in detail. U see, i have just begun with VC and my project is entirely graphics based (OpenGL). So its imperative that i get a good grasp on the drawing mechanism. Despo for your replys. Thanks.