» Как узнать класс окна (контрола) под курсором?

The WindowFromPoint function retrieves the handle of the window that contains the specified point.

HWND WindowFromPoint(

POINT Point // structure with point
);

The GetClassName function retrieves the name of the class to which the specified window belongs.

int GetClassName(

HWND hWnd, // handle of window
LPTSTR lpClassName, // address of buffer for class name
int nMaxCount // size of buffer, in characters
);