internal class CustomAppointmentElement : AppointmentElement
{
    private AppointmentsViewModel _appointmentsViewModel;
    private DockLayoutPanel _outerContainer;
    private StackLayoutElement _container;
    private LightVisualButtonElement _expandCollapseButton;
    private LightVisualElement _icon1;
    private LightVisualElement _icon2;
    private LightVisualElement _icon3;
    private LightVisualElement _timeText;
    private LightVisualElement _summaryText;
    private LightVisualElement _continueArrow;

    protected override void CreateChildElements()
    {
        base.CreateChildElements();
        this.Padding = new Padding(1, 0, 1, 0);

        _outerContainer = new DockLayoutPanel();
        _outerContainer.StretchHorizontally = true;
        _outerContainer.StretchVertically = true;
        _outerContainer.ShouldHandleMouseInput = false;
        _outerContainer.NotifyParentOnMouseInput = true;
        _outerContainer.LastChildFill = true;

        _continueArrow = new LightVisualElement();
        _continueArrow.Image = ArrowRightImage;
        _continueArrow.StretchHorizontally = false;

        _container = new StackLayoutElement();
        _container.Orientation = Orientation.Horizontal;
        _container.Alignment = ContentAlignment.MiddleLeft;
        _container.StretchHorizontally = false;
        _container.StretchVertically = true;
        _container.ShouldHandleMouseInput = false;
        _container.NotifyParentOnMouseInput = true;

        _expandCollapseButton = new LightVisualButtonElement();
        _expandCollapseButton.ShouldHandleMouseInput = true;
        _expandCollapseButton.Margin = new Padding(1, 1, 0, 1);
        _expandCollapseButton.NotifyParentOnMouseInput = false;
        _expandCollapseButton.Alignment = ContentAlignment.MiddleLeft;
        _expandCollapseButton.StretchHorizontally = false;
        _expandCollapseButton.StretchVertically = false;
        _expandCollapseButton.Click += _expandCollapseButton_Click;
        _expandCollapseButton.Image = GetButtonImage(false);

        _icon1 = new LightVisualElement();
        _icon1.ShouldHandleMouseInput = false;
        _icon1.Margin = new Padding(1, 1, 0, 1);
        _icon1.NotifyParentOnMouseInput = true;
        _icon1.Alignment = ContentAlignment.MiddleLeft;
        _icon1.StretchHorizontally = false;
        _icon1.StretchVertically = false;

        _icon2 = new LightVisualElement();
        _icon2.ShouldHandleMouseInput = false;
        _icon2.NotifyParentOnMouseInput = true;
        _icon2.Alignment = ContentAlignment.MiddleLeft;
        _icon2.StretchHorizontally = false;
        _icon2.StretchVertically = false;
        _icon2.Margin = new Padding(2, 1, 0, 1);

        _icon3 = new LightVisualElement();
        _icon3.ShouldHandleMouseInput = false;
        _icon3.NotifyParentOnMouseInput = true;
        _icon3.Alignment = ContentAlignment.MiddleLeft;
        _icon3.StretchHorizontally = false;
        _icon3.StretchVertically = false;
        _icon3.Margin = new Padding(2, 1, 0, 1);

        _timeText = new LightVisualElement();
        _timeText.Alignment = ContentAlignment.MiddleLeft;
        _timeText.ShouldHandleMouseInput = false;
        _timeText.NotifyParentOnMouseInput = true;
        _timeText.StretchHorizontally = false;
        _timeText.StretchVertically = false;
        _timeText.Margin = new Padding(2, 1, 2, 1);
        _timeText.ClipText = true;
        _timeText.TextWrap = false;
        _timeText.AutoEllipsis = true;

        _summaryText = new LightVisualElement();
        _summaryText.Alignment = ContentAlignment.MiddleLeft;
        _summaryText.ShouldHandleMouseInput = false;
        _summaryText.NotifyParentOnMouseInput = true;
        _summaryText.StretchHorizontally = false;
        _summaryText.StretchVertically = false;
        _summaryText.Margin = new Padding(2, 1, 2, 1);
        _summaryText.ClipText = true;
        _summaryText.TextWrap = false;
        _summaryText.AutoEllipsis = true;
        _summaryText.Font = new Font(_summaryText.Font, FontStyle.Bold);

        _container.Children.Add(_expandCollapseButton);
        _container.Children.Add(_icon1);
        _container.Children.Add(_icon2);
        _container.Children.Add(_icon3);
        _container.Children.Add(_timeText);
        _container.Children.Add(_summaryText);

        DockLayoutPanel.SetDock(_container, Telerik.WinControls.Layouts.Dock.Left);
        _outerContainer.Children.Add(_continueArrow);
        DockLayoutPanel.SetDock(_continueArrow, Telerik.WinControls.Layouts.Dock.Right);
        _outerContainer.Children.Add(_container);

        Children.Add(_outerContainer);
    }
}

 Public Class GridParameterValueElement
        Inherits GridDataCellElement

        Public Sub New(ByVal column As GridViewColumn, ByVal row As GridRowElement)
            MyBase.New(column, row)
        End Sub

        Private isInitialized As Boolean
        Private firstTimeIndexChanged As Boolean = True
        Private dropDown As RadDropDownListElement
        Private textBox As RadTextBoxElement
        Protected Overrides Sub CreateChildElements()
            MyBase.CreateChildElements()
            dropDown = New RadDropDownListElement() With { 
                .DropDownStyle = Telerik.WinControls.RadDropDownStyle.DropDownList
            }
            textBox = New RadTextBoxElement() With {
                .Enabled = True,
                .ClickMode = Telerik.WinControls.ClickMode.Press,
                .ZIndex = -1
            }
            If Me.Children.Contains(dropDown) Then Me.Children.Remove(dropDown)
            If Me.Children.Contains(textBox) Then Me.Children.Remove(textBox)
            Me.Children.Add(dropDown)
            Me.Children.Add(textBox)
            AddHandler dropDown.SelectedIndexChanged, AddressOf SelectedIndexChanged
            AddHandler textBox.TextChanged, AddressOf TextInBoxChanged
            'AddHandler textBox.Click, AddressOf TextBox_Click

        End Sub

        Protected Overrides Sub DisposeManagedResources()
            RemoveHandler dropDown.SelectedIndexChanged, AddressOf SelectedIndexChanged
            RemoveHandler textBox.TextChanged, AddressOf TextInBoxChanged
            MyBase.DisposeManagedResources()
        End Sub
            
        'Private Sub TextBox_Click(sender As Object, e As EventArgs)
        '    Dim test  = sender
        'End Sub


        Public Overrides Sub SetContent()
            MyBase.SetContent()

            If Me.RowInfo.Cells("DisplayValue").Tag IsNot Nothing Then

                If Not Me.isInitialized Then 
                    If Me.Children.Contains(textBox) Then Me.Children.Remove(textBox)

                    With Me.dropDown
                        .DataSource = Me.RowInfo.Cells("DisplayValue").Tag
                        .ValueMember = ("DevelopmentTypeParameterValueId")
                        .DisplayMember = ("ParameterValue")
                    End With 
                End If

                If Me.RowInfo.Tag IsNot Nothing Then
                    RemoveHandler dropDown.SelectedIndexChanged, AddressOf SelectedIndexChanged
                    dropDown.SelectedIndex = DirectCast(Me.RowInfo.Tag, Integer)
                    AddHandler dropDown.SelectedIndexChanged, AddressOf SelectedIndexChanged
                Else
                    RemoveHandler dropDown.SelectedIndexChanged, AddressOf SelectedIndexChanged
                    dropDown.SelectedIndex = -1
                    AddHandler dropDown.SelectedIndexChanged, AddressOf SelectedIndexChanged
                End If

            ElseIf Me.Value IsNot Nothing AndAlso Me.Value IsNot DBNull.Value Then

                If Not Me.isInitialized Then 
                    If Me.Children.Contains(dropDown) Then Me.Children.Remove(dropDown)
                    Me.textBox.Text = CStr(Me.Value)
                End If
       
            End If

            Me.isInitialized = True
        
        End Sub


        Protected Overrides ReadOnly Property ThemeEffectiveType() As Type
            Get
                Return GetType(GridDataCellElement)
            End Get
        End Property

        Public Overrides Function IsCompatible(ByVal data As GridViewColumn, ByVal context As Object) As Boolean
            Return TypeOf data Is GridViewParameterValueColumn AndAlso TypeOf context Is GridDataRowElement
        End Function

    End Class
    
    Public Class GridViewParameterValueColumn
        Inherits GridViewDataColumn
        Public Sub New(ByVal fieldName As String)
            MyBase.New(fieldName)
        End Sub
        Public Overrides Function GetCellType(ByVal row As GridViewRowInfo) As Type
            If TypeOf row Is GridViewDataRowInfo Then
                Return GetType(GridParameterValueElement)
            End If
            Return MyBase.GetCellType(row)
        End Function
    End Class