case WM_SIZE:
          if (message == WM_SIZE)
          {
               cxClient = LOWORD (lParam) ;
               cyClient = HIWORD (lParam) ;
          }
               // Calculate scrolling rectangle

          rectScroll.left   = 0 ;
          rectScroll.right  = cxClient ;
          rectScroll.top    = cyChar ;
          rectScroll.bottom = cyChar * (cyClient / cyChar) ;

          InvalidateRect (hwnd, NULL, TRUE) ;
          if (message == WM_INPUTLANGCHANGE)
               return true ;

          return 0 ;
          上边是WM_SIZE:的完整
问题是  请哪位大哥帮我看看return true ;
的作用 这块不懂  返回后是什么状况

The WM_INPUTLANGCHANGE message is sent to the topmost affected window after an application's input language has been changed. You should make any application-specific settings and pass the message to the DefWindowProc function, which passes the message to all first-level child windows. These child windows can pass the message to DefWindowProc to have it pass the message to their child windows, and so on.

A window receives this message through its WindowProc function.

摘自MSDN