I have a main window with several buttons. Eg. Button A & Button B. When I click Button A, it appears 2nd window. In the 2nd window, I create a Button Back. When I click Back, it closes the 2nd window and back to the main window without any problem. Then I click Button B, I imagine it will appear 3rd window. But no. Apparently the previous 2nd window appeared with the size of 3rd window. I coded wc.lpfnWndProc = WinProc3 which the function will process WinProc3 to create the window. I dont know whats the problem. Anyone has the same problem? But the weird things is, it only happens in occasion. Sometimes it worked perfectly. Im afraid i will have this problem when doing my presentation. Please. Help me.