อยากสั่งทำงานให้ DataGridView เลื่อนลงทีละ Cell หรือกดปุ่มทาง Button ให้ DataGridView แนะนำหน่อยคับ

Public Class Form2

    Private dtRegion As New DataTable("dtRegion") 'ภาค
    Private dtZone As New DataTable("dtZone") 'เขตการขาย/โซน
    Private parentBS As New BindingSource() 'อนุมานว่า ภาค
    Private childBS As New BindingSource() 'อนุนมานว่า เขตการขาย/โซน
    Private filteredChildBS As New BindingSource() 'อนุมานได้ว่า ภาค/โซน 

    Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        'add columns/rows in the Region table      
        dtRegion.Columns.Add(New DataColumn() With {.ColumnName = "RegionID", .DataType = GetType(Integer)})
        dtRegion.Columns.Add(New DataColumn() With {.ColumnName = "RegionDescription", .DataType = GetType(String)})
        dtRegion.Rows.Add(1, "ภาคเหนือ")
        dtRegion.Rows.Add(2, "ภาคใต้")
        dtRegion.Rows.Add(3, "ภาคตะวันตก")
        dtRegion.Rows.Add(4, "ภาคตะวันออก")

        'add some column/rows in the Zone table
        dtZone.Columns.Add(New DataColumn() With {.ColumnName = "ZoneID", .DataType = GetType(Integer)})
        dtZone.Columns.Add(New DataColumn() With {.ColumnName = "ZoneDescription", .DataType = GetType(String)})
        dtZone.Columns.Add(New DataColumn() With {.ColumnName = "RegionID", .DataType = GetType(Integer)})
        dtZone.Rows.Add(1, "ภาคเหนือ ผิวขาว", 1)
        dtZone.Rows.Add(2, "ภาคเหนือ อวบอูม", 1)
        dtZone.Rows.Add(1, "ภาคใต้ ผิวขาว", 2)
        dtZone.Rows.Add(2, "ภาคใต้ หอยงาม", 2)
        dtZone.Rows.Add(1, "ภาคตะวันตก ผิวขาว", 3)
        dtZone.Rows.Add(2, "ภาคตะวันตก หอยใหญ่", 3)
        dtZone.Rows.Add(1, "ภาคตะวันออก ผิวขาว", 4)
        dtZone.Rows.Add(2, "ภาคตะวันออก ระยองฮิสั้น จันฮิยาว", 4)
        dtZone.Rows.Add(3, "ภาคตะวันออก หอยหอม", 4)

        'Bound to a datatable
        Dim dtYET As New DataTable("dtYET")
        dtYET.Columns.Add(New DataColumn() With {.ColumnName = "RegionID", .DataType = GetType(Integer)})
        dtYET.Columns.Add(New DataColumn() With {.ColumnName = "ZoneID", .DataType = GetType(Integer)})
        '**************************************
        'Tricks
        '**************************************
        dtYET.Rows.Add(1, 1)
        dtYET.Rows.Add(2, 2)
        dtYET.Rows.Add(3, 3)
        dtYET.Rows.Add(4, 4)

        ' set up ParentBS and ChildBS and filteredChildBS
        parentBS.DataSource = dtRegion
        childBS.DataSource = dtZone

        filteredChildBS.DataSource = dtZone

        'bind the regionComboBoxColumn to the parentBS
        Me.regionComboBoxColumn.DataSource = parentBS
        Me.regionComboBoxColumn.DisplayMember = "RegionDescription"
        Me.regionComboBoxColumn.ValueMember = "RegionID"

        'bind the ZoneComboBoxColumn to the childBS
        Me.ZoneComboBoxColumn.DataSource = childBS
        Me.ZoneComboBoxColumn.DisplayMember = "ZoneDescription"
        Me.ZoneComboBoxColumn.ValueMember = "ZoneID"

        DataGridView1.AutoGenerateColumns = False
        DataGridView1.DataSource = dtYET
        DataGridView1.Columns(0).DataPropertyName = "RegionID"
        DataGridView1.Columns(1).DataPropertyName = "ZoneID"
    End Sub

    Private Sub DataGridView1_CellValueChanged(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellValueChanged
        Try
            If e.ColumnIndex = regionComboBoxColumn.Index Then
                If Me.DataGridView1.DataSource IsNot Nothing Then
                    If Me.DataGridView1.DataSource.GetType() = GetType(DataTable) Then
                        Me.DataGridView1.Rows(e.RowIndex).Cells(ZoneComboBoxColumn.Index).Value = DBNull.Value
                    Else
                        Me.DataGridView1.Rows(e.RowIndex).Cells(ZoneComboBoxColumn.Index).Value = Nothing
                    End If
                End If
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub

    Private Sub DataGridView1_DataError(sender As Object, e As DataGridViewDataErrorEventArgs) Handles DataGridView1.DataError
        If e.ColumnIndex <> ZoneComboBoxColumn.Index Then
            'MessageBox.Show("หอยงาม")
        End If
    End Sub

    Private Sub DataGridView1_EditingControlShowing(sender As Object, e As DataGridViewEditingControlShowingEventArgs) Handles DataGridView1.EditingControlShowing
        If Me.DataGridView1.CurrentCell.ColumnIndex = ZoneComboBoxColumn.Index Then
            Dim control As DataGridViewComboBoxEditingControl = TryCast(e.Control, DataGridViewComboBoxEditingControl)
            Dim bs As BindingSource = TryCast(control.DataSource, BindingSource)
            If bs IsNot Nothing Then
                ' set the filteredChildBS as the DataSource of the editing control
                TryCast(e.Control, ComboBox).DataSource = filteredChildBS
                Dim regionvalue As Object = Me.DataGridView1.Rows(Me.DataGridView1.CurrentCell.RowIndex).Cells(regionComboBoxColumn.Index).Value
                If regionvalue Is DBNull.Value OrElse regionvalue Is Nothing Then
                    filteredChildBS.Filter = "RegionID=-1"
                Else
                    filteredChildBS.Filter = "RegionID=" + regionvalue.ToString()
                End If
                ' set the SelectedValue property of the editing control
                If Me.DataGridView1.CurrentCell.Value IsNot DBNull.Value AndAlso Me.DataGridView1.CurrentCell.Value IsNot Nothing Then
                    control.SelectedValue = Me.DataGridView1.CurrentCell.Value
                End If
            End If
        End If
    End Sub

    Protected Overrides Function ProcessCmdKey(ByRef msg As Message, keyData As Keys) As Boolean
        If keyData = Keys.Enter Then
            SendKeys.Send("{TAB}")
            Return True
        End If
        Return MyBase.ProcessCmdKey(msg, keyData)
    End Function
End Class

Imports System.ComponentModel
Imports System.Windows.Forms
Imports System.Drawing
<ToolboxBitmap(GetType(DataGridView))> _
Public Class usrCtrGridControlExt : Inherits DataGridView
'...
'...
'...
'
End Class