Public Class frmTest
 
    Dim err_handler As New ErrorProvider
 
    Private Sub kd_stamm_Load(ByVal sender As System.Object, ByVal e As  _
        System.EventArgs) Handles MyBase.Load
        Me.KeyPreview = True
        Me.SetFocusHandler(Me)
    End Sub
 
    Private Sub SetFocusHandler(ByVal container As Control)
        For Each ctrl As Control In container.Controls
            If TypeOf (ctrl) Is TextBox Then
                AddHandler ctrl.KeyPress, AddressOf Me.Ctrl_Keypress
            End If
 
            If TypeOf (ctrl) Is Panel Or TypeOf (ctrl) Is GroupBox Or TypeOf ( _
              ctrl) Is TabControl Then
                Me.SetFocusHandler(ctrl)
            End If
        Next
    End Sub
 
    Private Sub Ctrl_Keypress(ByVal sender As Object, ByVal e As  _
      System.Windows.Forms.KeyPressEventArgs)
 
        Dim ctrl As Control = CType(sender, Control)
        Try
            With err_handler
                .SetIconAlignment(ctrl, ErrorIconAlignment.MiddleRight)
                .SetIconPadding(ctrl, 2)
                .BlinkStyle = ErrorBlinkStyle.BlinkIfDifferentError
            End With
            If IsNumeric(e.KeyChar) Then
                err_handler.Clear()
 
                'err_handler.SetError(ctrl, "")
            Else
                err_handler.SetError(ctrl, "Das ist ein Test")
 
                e.Handled = True
            End If
        Catch ex As Exception
            Debug.WriteLine(ex.Message)
        End Try
 
    End Sub
End Class