SetWindowRgn function user32

int SetWindowRgn(
  1. int hWnd,
  2. int hRgn,
  3. int bRedraw
)

The SetWindowRgn function sets the window region of a window. The window region determines the area within the window where the system permits drawing. The system does not display any portion of a window that lies outside of the window region

int SetWindowRgn(
  HWND hWnd,
  HRGN hRgn,
  BOOL bRedraw
);

Implementation

int SetWindowRgn(int hWnd, int hRgn, int bRedraw) =>
    _SetWindowRgn(hWnd, hRgn, bRedraw);