public MainWindow()
        {
            InitializeComponent();
            this.WindowState = WindowState.Maximized;
            avm = new ApplicationViewModel();
            this.DataContext = avm;

            ClientControl = new ClientsControl(avm);
            GridMain.Children.Add(ClientControl);
        }
        private void ListViewMenu_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            switch (((ListViewItem)((ListView)sender).SelectedItem).Name)
            {
            case "clients":
                try
                {
                    if (GridMain.Children.Count > 0 && GridMain.Children != null)
                    {
                        GridMain.Children.Clear();
                    }
                    ClientControl = new ClientsControl(avm);
                    GridMain.Children.Add(ClientControl);
                }
                catch (Exception err)
                {
                }

                break;

            case "projects":
                if (GridMain.Children.Count > 0 && GridMain.Children != null)
                {
                    GridMain.Children.Clear();
                }
                ProjectControl = new ProjectsControl(avm);
                GridMain.Children.Add(ProjectControl);
                break;

            case "payment":
                if (GridMain.Children.Count > 0 && GridMain.Children != null)
                {
                    GridMain.Children.Clear();
                }
                PaymentControl = new PaymentsControl(avm);
                GridMain.Children.Add(PaymentControl);
                break;

            default:
                break;
            }
        }