WNDCLASSEXW 结构

typedef struct tagWNDCLASSEXW {
  UINT      cbSize;
  UINT      style;
  //指向窗口过程的指针，类似js的事件，详见窗口过程一般设置lpfnWndProc = WndProc
  WNDPROC   lpfnWndProc;
  int       cbClsExtra;
  int       cbWndExtra;
  //窗口过程实例句柄
  HINSTANCE hInstance;
  //图标
  HICON     hIcon;
  //游标
  HCURSOR   hCursor;
  //背景画笔
  HBRUSH    hbrBackground;
  //菜单如果为NULL则默认没有菜单
  LPCWSTR   lpszMenuName;
  LPCWSTR   lpszClassName;
  HICON     hIconSm;
} WNDCLASSEXW, *PWNDCLASSEXW, *NPWNDCLASSEXW, *LPWNDCLASSEXW;

详细：官网