Why the recursive WM_Paint MSG don't occur

BOOL CALLBACK AboutDlgProc (HWND hDlg, UINT message, 
                            WPARAM wParam, LPARAM lParam)
{
	 PAINTSTRUCT ps;
     static HWND hCtrlBlock ;
     static int  iColor, iFigure ;
     
     switch (message)
     {
     case WM_PAINT:
          PaintTheBlock (hCtrlBlock, iColor, iFigure) ;
          break ;
     }
}

if (DialogBox (hInstance, TEXT ("AboutBox"), hwnd, AboutDlgProc))
     InvalidateRect (hwnd, NULL, TRUE) ;

void PaintTheBlock (HWND hCtrl, int iColor, int iFigure)
{
    InvalidateRect (hCtrl, NULL, TRUE) ;    //May motivate a paint MSG,but why don't ?
     UpdateWindow (hCtrl) ;
     PaintWindow (hCtrl, iColor, iFigure);
}

InvalidateRect (hCtrl, NULL, TRUE) ;    //May motivate a paint MSG,but why don't ?
 UpdateWindow (hCtrl) ;