Multitasking: restricting CPU usage

[Chrissie]

I'm currently working on a Multitasking Demo which comes from a Petzold book.

The app takes 99% of CPU usage, which makes it almost impossible to close it down, even causing system instability. Is it possible to restrict CPU usage?

LRESULT APIENTRY WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
     {
     static char   *szChildClass[] = { "Child1", "Child2",
                                       "Child3", "Child4" } ;
     static HWND    hwndChild[4] ;
     static WNDPROC ChildProc[] = { WndProc1, WndProc2,
                                    WndProc3, WndProc4 } ;
     HINSTANCE      hInstance ;
     int            i, cxClient, cyClient ;
     WNDCLASSEX     wndclass ;

     switch (iMsg)
          {
          case WM_CREATE :
               hInstance = (HINSTANCE) GetWindowLong (hwnd, GWL_HINSTANCE) ;

               wndclass.cbSize        = sizeof (wndclass) ;
               wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
               wndclass.cbClsExtra    = 0 ;
               wndclass.cbWndExtra    = 0 ;
               wndclass.hInstance     = hInstance ;
               wndclass.hIcon         = NULL ;
               wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
               wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
               wndclass.lpszMenuName  = NULL ;
               wndclass.hIconSm       = NULL ;

               for (i = 0 ; i < 4 ; i++)
                    {
                    wndclass.lpfnWndProc   = ChildProc[i] ;
                    wndclass.lpszClassName = szChildClass[i] ;

                    RegisterClassEx (&wndclass) ;

                    hwndChild[i] = CreateWindow (szChildClass[i], NULL,
                          WS_CHILDWINDOW | WS_BORDER | WS_VISIBLE,
                          0, 0, 0, 0, hwnd, (HMENU) i, hInstance, NULL) ;
                    }

               return 0 ;

          case WM_SIZE :
               cxClient = LOWORD (lParam) ;
               cyClient = HIWORD (lParam) ;

               for (i = 0 ; i < 4 ; i++)
                    MoveWindow (hwndChild[i], (i % 2) * cxClient / 2,
                                              (i > 1) * cyClient / 2,
                                cxClient / 2, cyClient / 2, TRUE) ;
               return 0 ;

          case WM_CHAR :
               if (wParam == '\x1B')
                    DestroyWindow (hwnd) ;

               return 0 ;

          case WM_DESTROY :
               PostQuitMessage (0) ;
               return 0 ;
          }
     return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
     }

[Kasracer]

You could always make it low priority