protected override void OnUpdateVisual()
{
base.OnUpdateVisual();
var first = FirstBlock;
if (first != null)
{
StringBuilder newText = GetValue(first);
if (!m_textbox.TextEquals(newText))
{
m_textbox.TextChanged -= m_textChanged;
m_textbox.SetText(newText);
m_textbox.TextChanged += m_textChanged;
}
}
}