Public Class BoitDataGridViewColumnRichText : Inherits DataGridViewColumn
    Public Sub New()
        CellTemplate = New DataGridViewRichTextCell
    End Sub
    Public Overrides Property CellTemplate() As DataGridViewCell
        Get
            Return MyBase.CellTemplate
        End Get
        Set(ByVal value As DataGridViewCell)
            If Not (value Is Nothing) AndAlso Not value.GetType().IsAssignableFrom(GetType(DataGridViewRichTextCell)) Then
                Throw New InvalidCastException("Must be a DataGridViewRichTextCell")
            End If
            MyBase.CellTemplate = value
        End Set
    End Property
End Class
Public Class DataGridViewRichTextCell
    Inherits DataGridViewTextBoxCell
    Public Overrides Sub InitializeEditingControl(ByVal rowIndex As Integer, _
          ByVal initialFormattedValue As Object, _
          ByVal dataGridViewCellStyle As DataGridViewCellStyle)
 
        MyBase.InitializeEditingControl(rowIndex, initialFormattedValue, dataGridViewCellStyle)
        Dim ctl As RichTextEditingControl = CType(DataGridView.EditingControl, RichTextEditingControl)
        ctl.Rtf = CType(Me.Value, String)
    End Sub
    Public Overrides ReadOnly Property EditType() As Type
        Get
            Return GetType(RichTextEditingControl)
        End Get
    End Property
    Public Overrides ReadOnly Property ValueType() As Type
        Get
            Return GetType(String)
        End Get
    End Property
    Public Overrides ReadOnly Property DefaultNewRowValue() As Object
        Get
            Return String.Empty
        End Get
    End Property
End Class
Class RichTextEditingControl
    Inherits RichTextBox
    Implements IDataGridViewEditingControl
 
    Private dataGridViewControl As DataGridView
    Private valueIsChanged As Boolean = False
    Private rowIndexNum As Integer
    Public Sub New()
        Me.MaxLength = 2000
        Me.Multiline = True
        Me.Font = New Font("Arial", 10)
    End Sub
    Public Property EditingControlFormattedValue() As Object _
        Implements IDataGridViewEditingControl.EditingControlFormattedValue
 
        Get
            Return Me.Text
        End Get
        Set(ByVal value As Object)
            If TypeOf value Is String Then
                Me.Text = CType(value, String)
            End If
        End Set
    End Property
    Public Function GetEditingControlFormattedValue(ByVal context _
        As DataGridViewDataErrorContexts) As Object _
        Implements IDataGridViewEditingControl.GetEditingControlFormattedValue
 
        Return Me.Text
    End Function
    Public Sub ApplyCellStyleToEditingControl(ByVal dataGridViewCellStyle As  _
        DataGridViewCellStyle) _
        Implements IDataGridViewEditingControl.ApplyCellStyleToEditingControl
 
        Me.Font = dataGridViewCellStyle.Font
    End Sub
    Public Property EditingControlRowIndex() As Integer _
        Implements IDataGridViewEditingControl.EditingControlRowIndex
 
        Get
            Return rowIndexNum
        End Get
        Set(ByVal value As Integer)
            rowIndexNum = value
        End Set
    End Property
 
    Public Function EditingControlWantsInputKey(ByVal key As Keys, _
        ByVal dataGridViewWantsInputKey As Boolean) As Boolean _
        Implements IDataGridViewEditingControl.EditingControlWantsInputKey
 
        Select Case key And Keys.KeyCode
            Case Keys.Left, Keys.Up, Keys.Down, Keys.Right, _
                Keys.Home, Keys.End, Keys.PageDown, Keys.PageUp
 
                Return True
 
            Case Else
                Return Not dataGridViewWantsInputKey
        End Select
 
    End Function
 
    Public Sub PrepareEditingControlForEdit(ByVal selectAll As Boolean) _
        Implements IDataGridViewEditingControl.PrepareEditingControlForEdit
 
    End Sub
 
    Public ReadOnly Property RepositionEditingControlOnValueChange() _
        As Boolean Implements _
        IDataGridViewEditingControl.RepositionEditingControlOnValueChange
 
        Get
            Return False
        End Get
 
    End Property
 
    Public Property EditingControlDataGridView() As DataGridView _
        Implements IDataGridViewEditingControl.EditingControlDataGridView
 
        Get
            Return dataGridViewControl
        End Get
        Set(ByVal value As DataGridView)
            dataGridViewControl = value
        End Set
 
    End Property
 
    Public Property EditingControlValueChanged() As Boolean _
        Implements IDataGridViewEditingControl.EditingControlValueChanged
 
        Get
            Return valueIsChanged
        End Get
        Set(ByVal value As Boolean)
            valueIsChanged = value
        End Set
 
    End Property
 
    Public ReadOnly Property EditingControlCursor() As Cursor _
        Implements IDataGridViewEditingControl.EditingPanelCursor
 
        Get
            Return MyBase.Cursor
        End Get
 
    End Property
 
End Class