<Grid VerticalAlignment=”Stretch” HorizontalAlignment=”Stretch”>
        <Grid.RowDefinitions>
            <RowDefinition Height=”*” />
            <RowDefinition Height=”Auto” />
            <RowDefinition Height=”*” />
        </Grid.RowDefinitions>
<GridSplitter 
            Grid.Row=”1&#8243; 
            Height=”3&#8243; 
            HorizontalAlignment=”Stretch” 
            VerticalAlignment=”Center” 
            Margin=”0&#8243;/>
</Grid> 

Grid gridti = new Grid();
RowDefinition rd1 = new RowDefinition();
rd1.Height = ???;   // <RowDefinition Height=”*” />
gridti.RowDefinitions.Add(rd1);
RowDefinition rd2 = new RowDefinition();
rd2.Height = GridLength.Auto;
gridti.RowDefinitions.Add(rd2);
RowDefinition rd3 = new RowDefinition();
rd3.Height = ???;    // <RowDefinition Height=”*” />
gridti.RowDefinitions.Add(rd3);
GridSplitter gsp = new GridSplitter();
??? // Grid.Row=”1&#8243;
gsp.Height = 3;
gsp.HorizontalAlignment = HorizontalAlignment.Stretch;
gsp.VerticalAlignment = VerticalAlignment.Center;
gsp.Margin = ???;    // Margin=”0&#8243;

<Grid VerticalAlignment=”Stretch” HorizontalAlignment=”Stretch”>
        <Grid.RowDefinitions>
            <RowDefinition Height=”*” />
            <RowDefinition Height=”Auto” />
            <RowDefinition Height=”*” />
        </Grid.RowDefinitions>
<GridSplitter 
            Grid.Row=”1"; 
            Height=”3"; 
            HorizontalAlignment=”Stretch” 
            VerticalAlignment=”Center” 
            Margin=”0"/>
</Grid> 

Grid gridti = new Grid();
RowDefinition rd1 = new RowDefinition();
rd1.Height = ???;   // <RowDefinition Height=”*” />
gridti.RowDefinitions.Add(rd1);
RowDefinition rd2 = new RowDefinition();
rd2.Height = GridLength.Auto;
gridti.RowDefinitions.Add(rd2);
RowDefinition rd3 = new RowDefinition();
rd3.Height = ???;    // <RowDefinition Height=”*” />
gridti.RowDefinitions.Add(rd3);
GridSplitter gsp = new GridSplitter();
??? // Grid.Row=”1"
gsp.Height = 3;
gsp.HorizontalAlignment = HorizontalAlignment.Stretch;
gsp.VerticalAlignment = VerticalAlignment.Center;
gsp.Margin = ???;    // Margin=”0"

<GridSplitter Grid.Row=”1"

Grid.SetRow(gsp, 1);

Grid gridti1 = new Grid();
Grid gridti2 = new Grid();

private void fillTree()
        {
            DataTable dt=selectData("select * from sTreeMenu where IdParent IS NULL");
            foreach (DataRow dr in dt.Rows)
            {
                TreeViewItem tvi = new TreeViewItem();
                tvi.Tag = dr[0];
                tvi.Header = dr[2].ToString();
                TreeMenu.Items.Add(tvi);
                fillTreeChild((Int32)dr[0], tvi);
                tvi.IsExpanded = true;
            }
        }

        private void fillTreeChild(Int32 idParent, TreeViewItem tvi)
        {
            DataTable dt = selectData("select * from sTreeMenu where IdParent = " + idParent.ToString() + " order by id");
            foreach (DataRow dr in dt.Rows)
            {
                TreeViewItem tvic = new TreeViewItem();
                tvic.Tag = dr[0];
                tvic.Header = dr[2].ToString();
                tvi.Items.Add(tvic);
                fillTreeChild((Int32)dr[0], tvic);
                tvi.IsExpanded = true;
            }
        }

        private void SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
        {
            if (TreeMenu.SelectedItem != null)
            {
                TreeViewItem tvi = (TreeViewItem)this.TreeMenu.SelectedItem;
                this.TabControl.Visibility = Visibility.Visible;
                TabItem ti = new TabItem();
                ti.Name = "ti" + tvi.Tag.ToString();
                ti.Header = tvi.Header;

                Grid gridti = new Grid();
                RowDefinition rd1 = new RowDefinition();
                rd1.Height = new GridLength(1, GridUnitType.Star);
                gridti.RowDefinitions.Add(rd1);
                RowDefinition rd2 = new RowDefinition();
                rd2.Height = GridLength.Auto;
                gridti.RowDefinitions.Add(rd2);
                RowDefinition rd3 = new RowDefinition();
                rd3.Height = new GridLength(1, GridUnitType.Star);
                gridti.RowDefinitions.Add(rd3);
                GridSplitter gsp = new GridSplitter();
                Grid.SetRow(gsp, 1);
                gsp.Background = new SolidColorBrush(Colors.Red);
                gsp.Height = 3;
                gsp.HorizontalAlignment = HorizontalAlignment.Stretch;
                gsp.VerticalAlignment = VerticalAlignment.Center;
                gsp.Margin = new Thickness(2);
                ti.Content = gridti;
                lTabItem.Add(ti);
                this.TabControl.Items.Add(ti);
                this.TabControl.SelectedItem = ti;
                //this.TreeMenu.IsEnabled = false;
                statusBar = this.StatusBar.Text;
                this.StatusBar.Text = "Панель " + ti.Header + " открыта.";
            }
        }

gridti.Children.Add(gsp);