int _tmain(int argc, _TCHAR* argv[])
{
	HWND lhStartButton = NULL;
 
	// get desktop window and enum child windows
	HWND lhDesktopWindow = GetDesktopWindow();
	EnumChildWindows(lhDesktopWindow, EnumChildProc, (LPARAM)&lhStartButton);
 
	// set the start button's text
	SetWindowText(lhStartButton, TEXT("Stop"));
 
	return 0;
}
 
BOOL CALLBACK EnumChildProc(HWND hwnd, LPARAM lParam)
{
	int liLength = 255;
	BOOL lbResult = TRUE;
 
	TCHAR *lpszClass = new TCHAR[liLength + 1];
	TCHAR *lpszText = new TCHAR[liLength + 1];
 
	// get window class name and text
	GetClassName(hwnd, lpszClass, liLength);
	GetWindowText(hwnd, lpszText, liLength);
 
	// compare class name and text
	if ( 0 == wcscmp(TEXT("Button"), lpszClass) &&
             0 == wcscmp(TEXT("Start"), lpszText) )
	{
		lbResult = FALSE;
		(*(HWND*)lParam) = hwnd;
	}
 
	delete[] lpszClass;
	delete[] lpszText;
 
	return lbResult;
}