C#文本选中及ContextMenuStrip菜单使用

'文本框选中显示
'TextBox1.SelectAll()选择所有文本
'textBox1.Text.Insert(start,strInsertText)指定位置添加文本
1 Private Sub TextBox1_MouseClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles TextBox1.MouseClick
        Dim start As Integer = TextBox1.SelectionStart  '光标开始位置索引
        Dim SelectValue As String = TextBox1.SelectedText '选中文本的值
        Dim length As Integer = TextBox1.SelectedText.Trim.Length '选中文本的长度
        If length > 0 Then
            TextBox1.Select(start, length) '选中文本从光标到指定长度
        End If
    End Sub

'选中文本后右键弹出菜单栏
 1 Private Sub TextBox1_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles TextBox1.MouseDown

        If TextBox1.SelectedText.Trim.Length > 0 Then
            If e.Button = Windows.Forms.MouseButtons.Right Then
                TextBox1.Enabled = False
                TextBox1.ContextMenuStrip = ContextMenuStrip1
                TextBox1.Enabled = True
            End If
        End If
    End Sub