These constants are used with the GetWindowLong and SetWindowLong functions.
#define GWL_USERDATA (-21) #define GWLP_USERDATA (-21) #define GWL_EXSTYLE (-20) #define GWL_STYLE (-16) #define GWL_ID (-12) #define GWLP_ID (-12) #define GWL_HWNDPARENT (-8) #define GWLP_HWNDPARENT (-8) #define GWL_HINSTANCE (-6) #define GWLP_HINSTANCE (-6) #define GWL_WNDPROC (-4) #define GWLP_WNDPROC (-4) #define DWL_MSGRESULT 0 #define DWLP_MSGRESULT 0 #define DWL_USER 8 #define DWLP_USER 8