The error is telling you that your declaration of MonitorFromWindow
conflicts with the prior declaration. The prior declaration in Winuser.h
declared the function with extern "C"
linkage, is __declspec(dllimport)
and has the __stdcall
calling convention.
You should remove your erroneous declaration and use that from the header file.
15
solved Windows7.1 SDK: C2373: “MonitorFromWindow” Redefinition