主题：文本框中查找到的字符，如何高亮显示？

Dim t1,t2 As String
t1=e.Form.Controls("TextBox1").text
t2=e.Form.Controls("TextBox2").text

e.Form.Controls("TextBox1").Select()
If t2 <> "" Then
    If Instr(t1,t2) <> 0 Then
        e.Form.Controls("TextBox1").SelectionStart = Instr(t1,t2)-1
        e.Form.Controls("TextBox1").SelectionLength = Len(t2)
    Else
        MessageBox.Show("没有找到!", "提示", MessageBoxButtons.ok, MessageBoxIcon.Question)
    End If
Else
    MessageBox.Show("请输入要查找的字符!", "提示", MessageBoxButtons.ok, MessageBoxIcon.Question)
End If