Public Class Form1
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        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 Or TypeOf (ctrl) Is ComboBox Then
                AddHandler ctrl.GotFocus, AddressOf Me.Ctrl_GotFocus
                AddHandler ctrl.LostFocus, AddressOf Me.Ctrl_LostFocus
            End If
 
            ' Rekursiv, d.h. für Textbox und Combobox in Panels oder Groupbox
            If TypeOf (ctrl) Is Panel Or TypeOf (ctrl) Is GroupBox Then
                Me.SetFocusHandler(ctrl)
            End If
        Next
    End Sub
 
    Private Sub Ctrl_GotFocus(ByVal sender As Object, ByVal e As _
      System.EventArgs)
        Try
            DirectCast(sender, Control).BackColor = Color.Bisque
        Catch ex As Exception
            Debug.WriteLine(ex.Message)
        End Try
    End Sub
 
    Private Sub Ctrl_LostFocus(ByVal sender As Object, ByVal e As _
      System.EventArgs)
        Try
            DirectCast(sender, Control).BackColor = Color.White
        Catch ex As Exception
            Debug.WriteLine(ex.Message)
        End Try
    End Sub
End Class