Отмена действия в DataGridview

Public Class Form1
    Public stac1 As Stack(Of String) = New Stack(Of String)
    Public stac2 As Stack(Of String) = New Stack(Of String)
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        If stac2.Count > 0 Then
            Dim str As String = stac2.Pop
            Dim dgg As DataGridView
            dgg = Me.Controls.Find(str.Split("^").First, True).FirstOrDefault
            Dim yy As IEnumerable(Of String) = str.Split("^").Skip(1).Take(2)
            Dim int1 As Integer = yy.FirstOrDefault
            Dim int2 As Integer = yy.LastOrDefault
            stac1.Push(dgg.Name & "^" & int1 & "^" & int2 & "^" & dgg.Item(int2, int1).Value)
            dgg.Item(int2, int1).Value = str.Split("^").Last
        End If
    End Sub
 
    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        If stac1.Count > 0 Then
            Dim str As String = stac1.Pop
            Dim dgg As DataGridView
            dgg = Me.Controls.Find(str.Split("^").First, True).FirstOrDefault
            Dim yy As IEnumerable(Of String) = str.Split("^").Skip(1).Take(2)
            Dim int1 As Integer = yy.FirstOrDefault
            Dim int2 As Integer = yy.LastOrDefault
            stac2.Push(dgg.Name & "^" & int1 & "^" & int2 & "^" & dgg.Item(int2, int1).Value)
            dgg.Item(int2, int1).Value = str.Split("^").Last
        End If
    End Sub
 
    Private Sub DataGridViewX1_CellClic(sender As DataGridView, e As DataGridViewCellEventArgs) Handles DataGridView1.CellEndEdit
        ChVl1(sender.CurrentCell)
    End Sub
 
    Private Sub DataGridViewX1_CellClick(sender As DataGridView, e As DataGridViewCellCancelEventArgs) Handles DataGridView1.CellBeginEdit
        ChVl(sender.Item(e.ColumnIndex, e.RowIndex))
    End Sub
 
    Public Sub ChVl(str As DataGridViewCell)
        TextBox1.Text = str.Value
    End Sub
 
    Public Sub ChVl1(str As DataGridViewCell)
        str.Value = If(str.Value = vbNullString, "Пусто", If(TextBox1.Text = str.Value, TextBox1.Text, str.Value))
        If TextBox1.Text <> str.Value Then
            stac1.Push(str.DataGridView.Name & "^" & str.RowIndex & "^" & str.ColumnIndex & "^" & TextBox1.Text)
        End If
        TextBox1.Text = vbNullString
    End Sub
End Class