creating a SuDoKu puzzle generator

Public Class Form2
    Inherits System.Windows.Forms.Form
    Public boxes(8, 8) As TextBox
    Public newbox As TextBox


    Private Sub Form2_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load


        Dim groupBoxes() As GroupBox = Me.Controls.OfType(Of GroupBox).OrderBy(Function(g) g.Name).ToArray
        Dim arrayIndex As Integer = 0
        Dim rowStartIndex As Integer = 0
        Dim rowCounter As Integer = 0
        Dim colCounter As Integer = 0

        For row As Integer = 0 To 8
            For col As Integer = 0 To 8

                'create a new textbox and set its properties
                newbox = New TextBox
                newbox.Size = New Drawing.Size(50, 30)
                newbox.Location = New Point(5 + colCounter * 70, 20 + rowCounter * 20 * 2)
                newbox.TextAlign = HorizontalAlignment.Center
                newbox.Font = New Font("Tahoma", 18, FontStyle.Bold)
                newbox.AllowDrop = True
                newbox.Clear()

                'connect it to a handler, save a reference to the array and add it to the form controls
                'AddHandler newbox.TextChanged, AddressOf TextBox_TextChanged
                AddHandler newbox.DragEnter, AddressOf TextBox_DragEnter
                AddHandler newbox.DragDrop, AddressOf TextBox_DragDrop

                boxes(row, col) = newbox

                Dim gb As GroupBox = groupBoxes(arrayIndex)
                gb.Controls.Add(newbox)
                colCounter += 1
                If colCounter = 3 Then colCounter = 0 : arrayIndex += 1
                If col = 8 Then arrayIndex = rowStartIndex

            Next
            rowCounter += 1
            If rowCounter = 3 Then rowCounter = 0 : arrayIndex += 3
            rowStartIndex = arrayIndex
        Next

        Label1.Text = IIf(Display = 1, "1", "A")
        Label2.Text = IIf(Display = 1, "2", "B")
        Label3.Text = IIf(Display = 1, "3", "C")
        Label4.Text = IIf(Display = 1, "4", "D")
        Label5.Text = IIf(Display = 1, "5", "E")
        Label6.Text = IIf(Display = 1, "6", "F")
        Label7.Text = IIf(Display = 1, "7", "G")
        Label8.Text = IIf(Display = 1, "8", "H")
        Label9.Text = IIf(Display = 1, "9", "I")

        Label16.Text = IIf(Autocheck = False, "Off", "On")
        Label16.ForeColor = IIf(Autocheck = False, Color.Black, Color.Red)
        Label17.Text = Microsoft.VisualBasic.Switch(Difficulty = 0, "Easy", Difficulty = 1, "Medium", Difficulty = 2, "Hard")
        Label17.ForeColor = Microsoft.VisualBasic.Switch(Difficulty = 0, Color.Green, Difficulty = 1, Color.Black, Difficulty = 2, Color.Red)
        Label18.Text = Microsoft.VisualBasic.Switch(Display = 0, "Letters", Display = 1, "Numbers")
        Label18.ForeColor = Microsoft.VisualBasic.Switch(Display = 0, Color.Red, Display = 1, Color.Black)
        Label19.Text = IIf(Sounds = False, "Off", "On")
        Label19.ForeColor = IIf(Sounds = False, Color.Black, Color.Red)


    End Sub

    Private Sub TextBox_DragEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs)
        ' Check the format of the data being dropped.
        If (e.Data.GetDataPresent(DataFormats.Text)) Then
            ' Display the copy cursor.
            e.Effect = DragDropEffects.Copy
        Else
            ' Display the no-drop cursor.
            e.Effect = DragDropEffects.None
        End If

    End Sub

    Private Sub TextBox_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs)
        newbox.Text = e.Data.GetData(DataFormats.Text)
    End Sub

    Private Sub SettingsToolStripMenuItem_Click(sender As System.Object, e As System.EventArgs) Handles SettingsToolStripMenuItem.Click
        Me.Hide()
        SetFrm.ShowDialog()
    End Sub

    Private Sub Label1_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Label1.MouseDown
        Label1.DoDragDrop(Label1.Text, DragDropEffects.Copy)
    End Sub

    Private Sub Label2_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Label2.MouseDown
        Label2.DoDragDrop(Label2.Text, DragDropEffects.Copy)
    End Sub

    Private Sub Label3_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Label3.MouseDown
        Label3.DoDragDrop(Label3.Text, DragDropEffects.Copy)
    End Sub

    Private Sub Label4_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Label4.MouseDown
        Label4.DoDragDrop(Label4.Text, DragDropEffects.Copy)
    End Sub

    Private Sub Label5_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Label5.MouseDown
        Label5.DoDragDrop(Label5.Text, DragDropEffects.Copy)
    End Sub

    Private Sub Label6_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Label6.MouseDown
        Label6.DoDragDrop(Label6.Text, DragDropEffects.Copy)
    End Sub

    Private Sub Label7_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Label7.MouseDown
        Label7.DoDragDrop(Label7.Text, DragDropEffects.Copy)
    End Sub

    Private Sub Label8_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Label8.MouseDown
        Label8.DoDragDrop(Label8.Text, DragDropEffects.Copy)
    End Sub

    Private Sub Label9_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Label9.MouseDown
        Label9.DoDragDrop(Label9.Text, DragDropEffects.Copy)
    End Sub
End Class