GUI_EndDialog()和WM_GetDialogItem()函数的作用是什么？

（1）void GUI_EndDialog(WM_HWIN hDialog, int r); 函数的形参R的作用是什么，看到有些程序是0，有些是1，不知道这是什么原因？
（2）WM_GetDialogItem()获取对话框句柄必须紧跟（方式1） case WM_INIT_DIALOG:后吗？我测试的时候，发现下面第2种方式获取句柄后无法关闭对话框；
方式1：
case WM_INIT_DIALOG:
  Fwin1 = WM_GetDialogItem(pMsg->hWin, ID_FRAMEWIN_1);
    hItem = WM_GetDialogItem(pMsg->hWin, ID_EDIT_0);
    EDIT_SetText(hItem, "");
    break;

方式2：
case WM_INIT_DIALOG:
    hItem = WM_GetDialogItem(pMsg->hWin, ID_EDIT_0);
    EDIT_SetText(hItem, "");   
    Fwin1 = WM_GetDialogItem(pMsg->hWin, ID_FRAMEWIN_1);   
    break;
回调函数如下：
static void _cbDialog1(WM_MESSAGE * pMsg) {
  WM_HWIN hItem;
  int     NCode;
  int     Id;
  // USER START (Optionally insert additional variables)
  // USER END
  WM_HWINFwin1;
  switch (pMsg->MsgId) {
  case WM_INIT_DIALOG:
   
   Fwin1 = WM_GetDialogItem(pMsg->hWin, ID_FRAMEWIN_1);
     hItem = WM_GetDialogItem(pMsg->hWin, ID_EDIT_0);
     EDIT_SetText(hItem, "");
     break;
  case WM_NOTIFY_PARENT:
    Id    = WM_GetId(pMsg->hWinSrc);
    NCode = pMsg->Data.v;
    switch(Id) {
    case ID_EDIT_0: // Notifications sent by 'Edit'
      switch(NCode) {
      case WM_NOTIFICATION_CLICKED:
        // USER START (Optionally insert code for reacting on notification message)
        // USER END
        break;
      case WM_NOTIFICATION_RELEASED:
        // USER START (Optionally insert code for reacting on notification message)
        // USER END
        break;
      case WM_NOTIFICATION_VALUE_CHANGED:
        // USER START (Optionally insert code for reacting on notification message)
        // USER END
        break;
      // USER START (Optionally insert additional code for further notification handling)
      // USER END
      }
      break;
    case ID_BUTTON_15: // Notifications sent by 'OK'
      switch(NCode) {
      case WM_NOTIFICATION_CLICKED:
        // USER START (Optionally insert code for reacting on notification message)
        // USER END
        break;
      case WM_NOTIFICATION_RELEASED:
        // USER START (Optionally insert code for reacting on notification message)
        // USER END
GUI_EndDialog(Fwin1,0);   
        break;
      // USER START (Optionally insert additional code for further notification handling)
      // USER END
      }
      break;
    // USER START (Optionally insert additional code for further Ids)
    // USER END
    }
    break;
  // USER START (Optionally insert additional message handling)
  // USER END
  default:
    WM_DefaultProc(pMsg);
    break;
  }
}