DefMDIChildProc function user32
Provides default processing for any window message that the window procedure of a multiple-document interface (MDI) child window does not process. A window message not processed by the window procedure must be passed to the DefMDIChildProc function, not to the DefWindowProc function.
LRESULT LRESULT DefMDIChildProcW(
HWND hWnd,
UINT uMsg,
WPARAM wParam,
LPARAM lParam
);
Implementation
int DefMDIChildProc(int hWnd, int uMsg, int wParam, int lParam) =>
_DefMDIChildProc(hWnd, uMsg, wParam, lParam);