[Browsable(false)]
public int SelectionLength { get; set; }

<Browsable(False)>
Public Property SelectionLength As Integer

using DevExpress.XtraEditors;

private void pasteBarButtonItem_ItemClick(object sender, DevExpress.XtraBars.ItemClickEventArgs e) {
    // Check if there is any text in the Clipboard to paste into the text editor.
    if (Clipboard.GetDataObject().GetDataPresent(DataFormats.Text)) {
        // Check if any text is selected in the text editor.
        if (textEdit1.SelectionLength > 0) {
            // Ask the user if they want to paste over the selected text.
            if (XtraMessageBox.Show("Do you want to paste over current selection?", "Paste", MessageBoxButtons.YesNo) == DialogResult.No)
                // Move selection to the point after the current selection and paste.
                textEdit1.SelectionStart = textEdit1.SelectionStart + textEdit1.SelectionLength;
        }
        // Paste the text into the text editor.
        textEdit1.Paste();
    }
}

private void cutBarButtonItem_ItemClick(object sender, DevExpress.XtraBars.ItemClickEventArgs e) {
    // Check if any text is selected in the text editor.   
    if (textEdit1.SelectedText.Length > 0)
        // Cut the selected text into the Clipboard.
        textEdit1.Cut();
}

private void copyBarButtonItem_ItemClick(object sender, DevExpress.XtraBars.ItemClickEventArgs e) {
    // Check if any text is selected in the text editor.   
    if (textEdit1.SelectionLength > 0)
        // Copy the selected text into the Clipboard.
        textEdit1.Copy();
}

Imports DevExpress.XtraEditors

Private Sub pasteBarButtonItem_ItemClick(ByVal sender As Object, ByVal e As DevExpress.XtraBars.ItemClickEventArgs) _
    Handles pasteBarButtonItem.ItemClick
    ' Check if there is any text in the Clipboard to paste into the text editor.
    If Clipboard.GetDataObject().GetDataPresent(DataFormats.Text) Then
        ' Check if any text is selected in the text editor.
        If textEdit1.SelectionLength > 0 Then
            ' Ask the user if they want to paste over the selected text.
            If XtraMessageBox.Show("Do you want to paste over current selection?", "Paste", MessageBoxButtons.YesNo) = DialogResult.No Then
                ' Move selection to the point after the current selection and paste.
                textEdit1.SelectionStart = textEdit1.SelectionStart + textEdit1.SelectionLength
            End If
        End If
        ' Paste the text into the text editor.
        textEdit1.Paste()
    End If
End Sub

Private Sub cutBarButtonItem_ItemClick(ByVal sender As Object, ByVal e As DevExpress.XtraBars.ItemClickEventArgs) _
    Handles cutBarButtonItem.ItemClick
    ' Check if any text is selected in the text editor.   
    If textEdit1.SelectedText.Length > 0 Then
        ' Cut the selected text into the Clipboard.
        textEdit1.Cut()
    End If
End Sub

Private Sub copyBarButtonItem_ItemClick(ByVal sender As Object, ByVal e As DevExpress.XtraBars.ItemClickEventArgs) _
    Handles copyBarButtonItem.ItemClick
    ' Check if any text is selected in the text editor.   
    If textEdit1.SelectionLength > 0 Then
        ' Copy the selected text into the Clipboard.
        textEdit1.Copy()
    End If
End Sub

if (storage.Appointments.IsNewAppointment(appointment)) {
    edtSubject.SelectionLength = 0;
    edtSubject.SelectionStart = edtSubject.Text.Length;

int selectionStart = teUriPattern.SelectionStart;
int selectionlength = teUriPattern.SelectionLength;
string text = teUriPattern.Text;

edit.SelectionStart = 1;
    edit.SelectionLength = 0;
}

If storage.Appointments.IsNewAppointment(appointment) Then
    edtSubject.SelectionLength = 0
    edtSubject.SelectionStart = edtSubject.Text.Length

Dim selectionStart As Integer = teUriPattern.SelectionStart
Dim selectionlength As Integer = teUriPattern.SelectionLength
Dim _text As String = teUriPattern.Text

edit.SelectionStart = 1
    edit.SelectionLength = 0
End If