Private Sub expenseTextboxKeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles expenseTextBox.KeyPress, revenueTextBox.KeyPress

'Handles for multiple textboxes

        Dim tb As TextBox = CType(sender, TextBox)
        Dim chr As Char = e.KeyChar

        If IsNumeric(e.KeyChar) And Not e.KeyChar = "-" Then
            'If adding the character to the end of the current TextBox value results in
            ' a numeric value, go on. Otherwise, set e.Handled to True, and don't let
            ' the character to be added.
            e.Handled = Not IsNumeric(tb.Text & e.KeyChar)

        ElseIf e.KeyChar = "." Then
            'For the decimal character (.) we need a different rule:
            'If adding a decimal to the end of the current value of the TextBox results
            ' in a numeric value, it can be added. If not, this means we already have a
            ' decimal in the TextBox value, so we only allow the new decimal to sit in
            ' when it is overwriting the previous decimal.
            If Not (tb.SelectedText = "." Or IsNumeric(tb.Text & e.KeyChar)) Then
                e.Handled = True
            End If

        ElseIf e.KeyChar = "-" Then
            'A negative sign is prevented if the "-" key is pressed in any location
            ' other than the begining of the number, or if the number already has a
            ' negative sign
            If tb.SelectionStart <> 0 Or Microsoft.VisualBasic.Left(tb.Text, 1) = "-" Then
                e.Handled = True
            End If

        ElseIf Not Char.IsControl(e.KeyChar) Then
            'IsControl is checked, because without that, keys like BackSpace couldn't
            ' work correctly.
            e.Handled = True
        End If
    End Sub