Thanks Ancient Dragon for the lead.
I studied it and found it needed both
#include "windows.h" and
#include "winuser.h" in the .cpp file that has the call.
But I get the dreaded linker error LNK2001; unresolved external symbol.
Do you have experience with that error?
Wow, THAT DID IT.
THANK YOU SO MUCH Ancient Dragon.
For anyone as beginner as I am, the .lib is loaded in Visual Studio by way of the Project tab. In there choose the last option xxx Properties Alt+F7.
Then click on the + of Configuration Properties, then the + of Linker and then Command Line. And at the bottom is Additional options: In huge space type User32.lib