   C++ Window Creation and DefWindowProc
  This probably has a really simple answer but I couldn''t really figure out why it happens. If I put the line,return DefWindowProc(hWnd, uMsg, wParam, lParam);in my WindowProc function, then my call to CreateWindowEx() will work perfectly, but if I change the above line to this,DefWindowProc(hWnd, uMsg, wParam, lParam);return 0L;then the call to CreateWindowEx() will fail.Why? 
  Because the return value is interpreted too.Some messages'' return value can indicate failure. This varies from message to message; a return value of 0L on WM_NCCREATE will tell windows that something went wrong and the window will be destroyed (or not even created).There is NO single return value which will tell success for every message. ;  Oh okay, I didn''t realize Windows had certain messages just for making a window. Thank you. 