procedure TfmMain.Timer1Timer(Sender: TObject);
var  vLastInputInfo: TLastInputInfo;
begin
    vLastInputInfo.cbSize := SizeOf(vLastInputInfo);
    GetLastInputInfo(vLastInputInfo);
    if GetTickCount - vLastInputInfo.dwTime > pingbao then
    begin
       if IsIconic(Application.Handle) then
       begin
        DefWindowProc(Application.Handle, WM_SYSCOMMAND, SC_RESTORE, 0);
       end;
       SetWindowPos(fmMain.handle,HWND_TOPMOST,0,0,0,0,SWP_NOMOVE or SWP_NOSIZE);
       fmMain.Visible := true;
    end;
end;   

代码功能：一定时间内检测不到鼠标或键盘的活动，则将窗体显示到前端！XP下测试通过！