How to maximize the Float Window while double clicking the header in WinForms Docking Manager?

public partial class Form1 : MetroForm
{
  #region Constructor
  public Form1()
  {
    InitializeComponent();
    this.dockingManager1.EnableDoubleClickOnCaption = true;
    this.dockingManager1.DockControlDeactivated += new            DockActivationChangedEventHandler(dockingManager1_DockControlDeactivated);
    this.dockingManager1.DockControlActivated += new DockActivationChangedEventHandler(dockingManager1_DockControlActivated);
    dockingManager1.DockStateChanged += new DockStateChangeEventHandler(dockingManager1_DockStateChanged);
    this.dockingManager1.OnCaptionDoubleClick += new Syncfusion.Windows.Forms.Tools.DockMouseSelectionEventHandler(dockingManager1_OnCaptionDoubleClick);
  }
  #endregion
 
  #region Events
  //Triggers when control lost its focus.
  void dockingManager1_DockControlDeactivated(object sender, DockActivationChangedEventArgs arg)
  {
    if (dockingManager1.IsFloating(arg.Control))
      dockingManager1.EnableDoubleClickOnCaption = false;
  }
 
  //Triggers when the control got the Focus.
  void dockingManager1_DockControlActivated(object sender, DockActivationChangedEventArgs arg)
  {
    if (!(dockingManager1.IsFloating(arg.Control)))
      dockingManager1.EnableDoubleClickOnCaption = true;
    else
      dockingManager1.EnableDoubleClickOnCaption = false;
 
  }
 
  //Triggers when the dock state changed(Dock state or Floating state or tabbed docking)
  void dockingManager1_DockStateChanged(object sender, DockStateChangeEventArgs arg)
  {
    if (dockingManager1.IsFloating(arg.Controls[0]))
      dockingManager1.EnableDoubleClickOnCaption = false;
    else
      dockingManager1.EnableDoubleClickOnCaption = true;
  }
 
  //Event triggeres on double click on the caption bar.
  void dockingManager1_OnCaptionDoubleClick(object sender, Syncfusion.Windows.Forms.Tools.DockControlMouseSelection arg)
  {
    if (this.dockingManager1.IsFloating(arg.Control))
    {
      Control argctrl = arg.Control;
      if ((arg.Control.TopLevelControl as FloatingForm).WindowState != FormWindowState.Maximized)
        (arg.Control.TopLevelControl as FloatingForm).WindowState = FormWindowState.Maximized;
      else
        (arg.Control.TopLevelControl as FloatingForm).WindowState = FormWindowState.Normal;
    }
  }
  #endregion
}

Partial Public Class Form1
   Inherits MetroForm
   #Region "Constructor"
   Public Sub New()
      InitializeComponent()
      Me.dockingManager1.EnableDoubleClickOnCaption = True
      AddHandler dockingManager1.DockControlDeactivated, AddressOf dockingManager1_DockControlDeactivated
      AddHandler dockingManager1.DockControlActivated, AddressOf dockingManager1_DockControlActivated
      AddHandler dockingManager1.DockStateChanged, AddressOf dockingManager1_DockStateChanged
      AddHandler dockingManager1.OnCaptionDoubleClick, AddressOf dockingManager1_OnCaptionDoubleClick
   End Sub
   #End Region
 
   #Region "Events"
   'Triggers when control lost its focus.
   Private Sub dockingManager1_DockControlDeactivated(ByVal sender As Object, ByVal arg As DockActivationChangedEventArgs)
      If dockingManager1.IsFloating(arg.Control) Then
        dockingManager1.EnableDoubleClickOnCaption = False
      End If
   End Sub
 
   'Triggers when the control got the Focus.
   Private Sub dockingManager1_DockControlActivated(ByVal sender As Object, ByVal arg As DockActivationChangedEventArgs)
      If Not(dockingManager1.IsFloating(arg.Control)) Then
        dockingManager1.EnableDoubleClickOnCaption = True
      Else
        dockingManager1.EnableDoubleClickOnCaption = False
      End If
   End Sub
 
   'Triggers when the dock state changed(Dock state or Floating state or tabbed docking)
   Private Sub dockingManager1_DockStateChanged(ByVal sender As Object, ByVal arg As DockStateChangeEventArgs)
      If dockingManager1.IsFloating(arg.Controls(0)) Then
    dockingManager1.EnableDoubleClickOnCaption = False
      Else
        dockingManager1.EnableDoubleClickOnCaption = True
      End If
   End Sub
 
   'Event triggeres on double click on the caption bar.
   Private Sub dockingManager1_OnCaptionDoubleClick(ByVal sender As Object, ByVal arg As Syncfusion.Windows.Forms.Tools.DockControlMouseSelection)
      If Me.dockingManager1.IsFloating(arg.Control) Then
        Dim argctrl As Control = arg.Control
        If (TryCast(arg.Control.TopLevelControl, FloatingForm)).WindowState <> FormWindowState.Maximized Then
          TryCast(arg.Control.TopLevelControl, FloatingForm).WindowState = FormWindowState.Maximized
    Else
          TryCast(arg.Control.TopLevelControl, FloatingForm).WindowState = FormWindowState.Normal
    End If
      End If
   End Sub
   #End Region
End Class