void CMyDlg::OnButton1()
{
int Iconw=GetSystemMetrics(SM_CXICON);
HKEY hKey;
RegOpenKeyEx(HKEY_CURRENT_USER,_T("Control Panel//Desktop//WindowMetrics"),0,KEY_ALL_ACCESS,&hKey);
TCHAR buff[20];
ZeroMemory(buff,sizeof(buff));
wsprintf(buff,_T("%d"),Iconw-1);
RegSetValueEx(hKey,_T("Shell Icon Size"),0,REG_SZ,(PBYTE)buff,sizeof(buff));
::SendMessage(HWND_BROADCAST,WM_WININICHANGE,0,0);
ZeroMemory(buff,sizeof(buff));
wsprintf(buff,_T("%d"),Iconw);
RegSetValueEx(hKey,_T("Shell Icon Size"),0,REG_SZ,(PBYTE)buff,sizeof(buff));
::SendMessage(HWND_BROADCAST,WM_WININICHANGE,0,0);
RegCloseKey(hKey);
// ::SHChangeNotify( SHCNE_ASSOCCHANGED , SHCNF_IDLIST | SHCNF_FLUSH, 0, 0);
// ::SendMessage( ::GetDesktopWindow(), WM_KEYDOWN, VK_F5, 0);
// ::SendMessage( ::GetDesktopWindow(), WM_KEYUP, VK_F5, 0);
}