Numeric Textbox 2 Decimal places

I am hoping this is not inappropriate to do on here if it is I apologize in advance and will let the thread die a slow agonizing death.
Here goes:
I have a little TextBox app that's supposed to only allow numeric’s positive and negative and allow 2 decimal places. I have tested it and it seems to work as intended. What I'd like is for you all to try and break it. The max characters functionality needs some work but it's not the focus of my TextBox.

'K. W. 4/19/2012
'TextBox Control For
'Numerics/Money entry
'1 Decimal Point
'2 Decimal Places
'Allows The BackSpace
'Handles enter key by Moving to the Next control
'Set Max characters checked - this sets it to 4 if not checked allows 10 characters
'The button just multiplies the textbox value by 5


Public Class Form1


    Private maxSize As Boolean = False
    Private numMaxSize As Integer


    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click


        If T1.Text <> "" Then
            If CDbl(T1.Text) > 0 Or CDbl(T1.Text) < 0 Then
                MsgBox(CDbl(T1.Text) * 5)
                T1.Clear()
            End If
        End If
        GetNextControl(Button1, False).Focus()
    End Sub


    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load


        'Add Handler for all the Numeric only TextBoxes on the Form
        For Each ctrl As Control In Me.Controls
            If TypeOf ctrl Is TextBox Then
                AddHandler ctrl.KeyPress, AddressOf Boxkeypress
            End If
        Next ctrl
        T1.MaxLength = 10
    End Sub


    Private Sub Boxkeypress(ByVal sender As Object, ByVal e As KeyPressEventArgs)


        Dim txt As TextBox = CType(sender, TextBox)


        If Not Char.IsDigit(e.KeyChar) Then e.Handled = True
        If e.KeyChar = "." And txt.Text.IndexOf(".") = -1 Then e.Handled = False 'allow single decimal point
        If e.KeyChar = "-" And txt.SelectionStart = 0 Then e.Handled = False 'allow negative number


        'Enter key move to next control
        If e.KeyChar = Chr(13) Then
            GetNextControl(txt, True).Focus()


            'If only a decimal point is in the box clear TextBox
            If e.KeyChar = Chr(13) And txt.Text = "." Then txt.Clear()
            Exit Sub
        End If


        Dim i As Integer = txt.Text.IndexOf(".")
        Dim len As Integer = txt.Text.Length


        'Allow only 2 Decimal places
        If Not e.Handled Then
            If i = -1 Then
                e.Handled = False
            Else
                If (len - i) > 2 Then e.Handled = True
            End If
        End If


        If e.KeyChar = Chr(8) Then e.Handled = False 'allow Backspace


    End Sub




    Private Sub chkMaxSize_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles chkMaxSize.CheckedChanged


        If chkMaxSize.Checked Then
            maxSize = True
            T1.MaxLength = 4
        Else
            maxSize = False
            T1.MaxLength = 10
        End If


    End Sub


End Class
 
 
sumber : http://www.daniweb.com/software-development/vbnet/threads/434461/numeric-textbox-2-decimal-places