Public Structure BufferEntry
   Dim rtbText As String
   Dim CursorPos As Integer
 
   Public Sub New(ByVal Text As String, ByVal Pos As Integer)
      Me.rtbText = Text
      Me.CursorPos = Pos
   End Sub
End Structure
 
 
Public Class rtbUndo
   Private buffer As System.Collections.Stack
 
   Public Sub New(ByVal CountElements As Integer)
      buffer = New System.Collections.Stack(CountElements)
   End Sub
 
   Public ReadOnly Property Count() As Integer
      Get
         Return buffer.Count
      End Get
   End Property
 
   Public Sub Add(ByVal rtbBufferEntry As BufferEntry)
      buffer.Push(rtbBufferEntry)
   End Sub
 
   Public Function Undo() As BufferEntry
      Return buffer.Pop
   End Function
End Class

Public Class Form1
   Private rtbBuffer As New rtbUndo(500)
   Private isBufferUpdate As Boolean = False
 
   Private Sub RichTextBox1_TextChanged(ByVal sender As System.Object, ByVal e _
     As System.EventArgs) Handles RichTextBox1.TextChanged
      If Not isBufferUpdate Then
         rtbBuffer.Add(New BufferEntry(Me.RichTextBox1.Rtf, _
           Me.RichTextBox1.SelectionStart))
      End If
   End Sub
 
   Private Sub RichTextBox1_KeyDown(ByVal sender As System.Object, ByVal e As _
     System.Windows.Forms.KeyEventArgs) Handles RichTextBox1.KeyDown
      If e.Control AndAlso e.KeyCode = Keys.Z Then
         If rtbBuffer.Count > 0 Then
            isBufferUpdate = True
            Dim bEntry As BufferEntry = rtbBuffer.Undo()
            Me.RichTextBox1.Rtf = bEntry.rtbText
            Me.RichTextBox1.SelectionStart = bEntry.CursorPos
            isBufferUpdate = False
         End If
         e.Handled = True
      End If
   End Sub
End Class

Gru?
---------------------------------------------------
Snoopy sagt - vb@rchiv find ich gut...
Schon gesehen? OSMMapViewer V2 Control