バージョン

SelectionStart プロパティ (XamTextEditor)

選択したテキストの場所を取得または設定します。テキストが選択されなければ、このプロパティはカレットの位置を返します。
シンタックス
'宣言
 
Public Property SelectionStart As Integer
public int SelectionStart {get; set;}
解説

SelectionStart は、現在のテキスト選択の開始場所を返します。何も選択されない場合は、カレットの場所を返します。このプロパティを設定して、選択したテキストを変更できます。このプロパティの設定は、コントロールのコンテンツを変更しません。

使用例
Private Sub Button1_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
        ' Make sure the editor is in edit mode. The following operations
        ' are only valid during edit mode. You can set IsAlwaysInEditMode
        ' to True so this step is not necessary as the editor will always
        ' be in edit mode.
        Me.textEditor1.StartEditMode()

        Me.textEditor1.Value = "Test"

        ' Select 3 characters starting from character position 1.
        Me.textEditor1.SelectionStart = 1
        Me.textEditor1.SelectionLength = 3

        ' This will print out the selected text which is "est".
        Dim selectedText As String = Me.textEditor1.SelectedText
        Debug.WriteLine("SelectedText = " & selectedText)

        ' Setting the SelectedText will delete the selected text
        ' and in its place insert the specified text. If nothing
        ' is currently selected then the specified text will be 
        ' inserted at the caret location.
        Me.textEditor1.SelectedText = "EST"

        ' SelectAll will select all of the text.
        Me.textEditor1.SelectAll()

        ' The following two lines perform the same operation as SelectAll.
        ' TextLength property returns the length of text in the editor.
        Me.textEditor1.SelectionStart = 0
        Me.textEditor1.SelectionLength = Me.textEditor1.TextLength
    End Sub
public void button1_Click( object sender, RoutedEventArgs e )
{
	// Make sure the editor is in edit mode. The following operations
	// are only valid during edit mode. You can set IsAlwaysInEditMode
	// to True so this step is not necessary as the editor will always
	// be in edit mode.
	this.textEditor1.StartEditMode( );

	this.textEditor1.Value = "Test";

	// Select 3 characters starting from character position 1.
	this.textEditor1.SelectionStart = 1;
	this.textEditor1.SelectionLength = 3;

	// This will print out the selected text which is "est".
	string selectedText = this.textEditor1.SelectedText;
	Debug.WriteLine( "SelectedText = " + selectedText );

	// Setting the SelectedText will delete the selected text
	// and in its place insert the specified text. If nothing
	// is currently selected then the specified text will be 
	// inserted at the caret location.
	this.textEditor1.SelectedText = "EST";

	// SelectAll will select all of the text.
	this.textEditor1.SelectAll( );

	// The following two lines perform the same operation as SelectAll.
	// TextLength property returns the length of text in the editor.
	this.textEditor1.SelectionStart = 0;
	this.textEditor1.SelectionLength = this.textEditor1.TextLength;
}
<igEditors:XamTextEditor x:Name="textEditor1"  />
参照