dockLayoutManager.DockController.AddPanel(DockType.Right);

dockLayoutManager.DockController.AddPanel(DockType.Right)

dockLayoutManager.DockController.Dock(layoutPanel1, layoutGroup1, DockType.Right);

dockLayoutManager.DockController.Dock(layoutPanel1, layoutGroup1, DockType.Right

dockLayoutManager.DockController.Insert(layoutGroup1, layoutPanel1, 2);

dockLayoutManager.DockController.Insert(layoutGroup1, layoutPanel1, 2)

dockLayoutManager.DockController.AddPanel(new Point(0, 0), new Size(100, 100));

dockLayoutManager.DockController.AddPanel(new Point(0, 0), new Size(100, 100))

dockLayoutManager.DockController.RemovePanel(layoutPanel1);

dockLayoutManager.DockController.RemovePanel(layoutPanel1)

//Add a layout panel to an existing LayoutGroup.
dockLayoutManager.DockController.Dock(layoutPanel1, layoutGroup1, DockType.Left);

'Add a layout panel to an existing LayoutGroup.
dockLayoutManager.DockController.Dock(layoutPanel1, layoutGroup1, DockType.Left)

dockLayoutManager.DockController.Insert(layoutGroup1, layoutPanel1, 2);

dockLayoutManager.DockController.Insert(layoutGroup1, layoutPanel1, 2)

dockLayoutManager.DockController.Dock(layoutPanel1, tabbedGroup1, DockType.Fill);

dockLayoutManager.DockController.Dock(layoutPanel1, tabbedGroup1, DockType.Fill)

dockLayoutManager.DockController.Dock(layoutPanel1, layoutPanel2, DockType.Right);

dockLayoutManager.DockController.Dock(layoutPanel1, layoutPanel2, DockType.Right)

dockLayoutManager.DockController.Dock(layoutPanel1, layoutPanel2, DockType.Fill);

dockLayoutManager.DockController.Dock(layoutPanel1, layoutPanel2, DockType.Fill)

dockLayoutManager.DockController.Dock(layoutPanel1, floatGroup, DockType.Right);

dockLayoutManager.DockController.Dock(layoutPanel1, floatGroup, DockType.Right)

dockLayoutManager.DockController.Insert(floatGroup, layoutPanel1, 0);

dockLayoutManager.DockController.Insert(floatGroup, layoutPanel1, 0)

//Adds a LayoutPanel to the left edge of the FloatGroup
dockLayoutManager.DockController.Dock(layoutPanel1, autoHideGroup, DockType.Left);

//Adds a LayoutPanel to the left edge of the FloatGroup
dockLayoutManager.DockController.Insert(autoHideGroup, layoutPanel1, 0);

'Add a LayoutPanel to the left edge of the FloatGroup
dockLayoutManager.DockController.Dock(layoutPanel1, autoHideGroup, DockType.Left)

'Add a LayoutPanel to the left edge of the FloatGroup
dockLayoutManager.DockController.Insert(autoHideGroup, layoutPanel1, 0)

dockLayoutManager1.LayoutController.Move(item1, group1, DevExpress.Xpf.Layout.Core.MoveType.InsideGroup);

dockLayoutManager1.LayoutController.Move(item1, group1, DevExpress.Xpf.Layout.Core.MoveType.InsideGroup)

dockLayoutManager.DockController.Float(layoutPanel1);

dockLayoutManager.DockController.Float(layoutPanel1)

//Hides a LayoutPanel at the nearest edge of the DockLayoutManager
dockLayoutManager.DockController.Hide(layoutPanel1);

//Hides a LayoutPanel within the specified AutoHideGroup
dockLayoutManager.DockController.Hide(layoutPanel1, autoHideGroup);

//Hides a LayoutPanel at the specified edge of the DockLayoutManager
dockLayoutManager.DockController.Hide(layoutPanel1, Dock.Left);

'Hides a LayoutPanel at the nearest edge of the DockLayoutManager.
dockLayoutManager.DockController.Hide(layoutPanel1)

'Hides a LayoutPanel within the specified AutoHideGroup.
dockLayoutManager.DockController.Hide(layoutPanel1, autoHideGroup)

'Hides a LayoutPanel at the specified edge of the DockLayoutManager.
dockLayoutManager.DockController.Hide(layoutPanel1, Dock.Left)

dockLayoutManager.DockController.Close(layoutPanel1);

dockLayoutManager.DockController.Close(layoutPanel1)

dockLayoutManager.DockController.Restore(layoutPanel1);

dockLayoutManager.DockController.Restore(layoutPanel1)

dockLayoutManager.DockController.Dock(layoutPanel1, layoutGroup1, DockType.Right);

dockLayoutManager.DockController.Insert(layoutGroup2, layoutPanel1, 0);

dockLayoutManager.DockController.Dock(layoutPanel1, layoutGroup1, DockType.Right)

dockLayoutManager.DockController.Insert(layoutGroup2, layoutPanel1, 0)

layoutPanel1.Visibility = Visibility.Hidden;

layoutPanel1.Visibility = Visibility.Visible;

layoutPanel1.Visibility = Visibility.Hidden

layoutPanel1.Visibility = Visibility.Visible

<Window ...
        xmlns:dxdo="http://schemas.devexpress.com/winfx/2008/xaml/docking">
    <Grid>
        <dxdo:DockLayoutManager x:Name="lmManager">
            <dxdo:LayoutGroup Orientation="Horizontal">
                <dxdo:LayoutPanel>
                    <Button Content="Explore" Click="Button_Click" />
                </dxdo:LayoutPanel>
                <dxdo:DocumentGroup x:Name="dcgExplorer">
                    <dxdo:DocumentPanel x:Name="paneDocument1" Caption="Document 1">
                        <RichTextBox />
                    </dxdo:DocumentPanel>
                    <dxdo:DocumentPanel x:Name="paneDocument2" Caption="Document 2">
                        <RichTextBox />
                    </dxdo:DocumentPanel>
                </dxdo:DocumentGroup>
            </dxdo:LayoutGroup>
        </dxdo:DockLayoutManager>
    </Grid>
</Window>

using DevExpress.Xpf.Docking;

// ...
    public partial class MainWindow : Window {
        private void CreateDocumentPanel(string name) {
            DocumentPanel modulePanel = new DocumentPanel() {
                Caption = name,
                IsActive = true
            };
            dcgExplorer.Add(modulePanel);
            modulPanel.Content = new Uri(@"Forms\TableDesignWindow.xaml", UriKind.Relative);
        }
        private void Button_Click(object sender, RoutedEventArgs e){
            CreateMdiChild("Test");
        }
    }

Imports DevExpress.Xpf.Docking

Public Partial Class MainWindow
    Inherits Window
    Private Sub CreateDocumentPanel(ByVal name As String)
        Dim modulePanel As DocumentPanel = New DocumentPanel() With {
            .Caption = name,
            .IsActive = True
        }
        dcgExplorer.Add(modulePanel)
        modulPanel.Content = New Uri("Forms\TableDesignWindow.xaml", UriKind.Relative)
    End Sub

    Private Sub Button_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
        CreateMdiChild("Test")
    End Sub
End Class

<dxdo:DockLayoutManager DockItemActivating="DockLayoutManager_DockItemActivating">
    <dxdo:LayoutGroup>
        <dxdo:DocumentGroup>
            <dxdo:DocumentPanel Caption="Document1" />
            <dxdo:DocumentPanel Caption="Document2" />
        </dxdo:DocumentGroup>
    </dxdo:LayoutGroup>
</dxdo:DockLayoutManager>

void DockLayoutManager_DockItemActivating(object sender, ItemCancelEventArgs e) {
    if (/*Your conditions here*/) {
        e.Cancel = true;
        e.Handled = true;
    }
}

Private Sub DockLayoutManager_DockItemActivating(ByVal sender As Object, ByVal e As ItemCancelEventArgs)
    e.Cancel = True
    e.Handled = True
End Sub

var panels1 = dockLayoutManager.GetItems().Where(x => x is LayoutPanel);
// or
var panels2 = dockLayoutManager.GetItems().OfType<LayoutPanel>();

Dim panels1 = dockLayoutManager.GetItems().Where(Function(x) TypeOf x Is LayoutPanel)
`... or 
Dim panels2 = dockLayoutManager.GetItems().OfType(Of LayoutPanel)()

public static class DockLayoutManagerExtension {
    // ...
    public static BaseLayoutItem[] GetItems(this DockLayoutManager container);
    // ...
}

Imports System.Runtime.CompilerServices

Module DockLayoutManagerExtension <Extension()>
    Function GetItems(ByVal container As DockLayoutManager) As BaseLayoutItem()
End Module

<Button Command="dxdo:DockControllerCommand.Close" CommandTarget="{Binding ElementName=dockManager1}" 
        CommandParameter="{Binding ElementName=dockManager1, Path=ActiveDockItem }">