# How to: Specify Whether a Hyperlink is Underlined

The Hyperlink object is an inline-level flow content element that allows you to host hyperlinks within the flow content. By default, Hyperlink uses a TextDecoration object to display an underline. TextDecoration objects can be performance intensive to instantiate, particularly if you have many Hyperlink objects. If you make extensive use of Hyperlink elements, you may want to consider showing an underline only when triggering an event, such as the MouseEnter event.

In the following example, the underline for the "My MSN" link is dynamic, that is, it only appears when the MouseEnter event is triggered.

## Example

The following markup sample shows a Hyperlink defined with and without an underline:

<!-- Hyperlink with default underline. -->
MSN Home

<Run Text=" | " />

<!-- Hyperlink with no underline. -->
MouseEnter="OnMouseEnter"
MouseLeave="OnMouseLeave"
NavigateUri="http://www.msn.com">
My MSN


The following code sample shows how to create an underline for the Hyperlink on the MouseEnter event, and remove it on the MouseLeave event.

// Display the underline on only the MouseEnter event.
private void OnMouseEnter(object sender, EventArgs e)
{
}

// Remove the underline on the MouseLeave event.
private void OnMouseLeave(object sender, EventArgs e)
{
}

' Display the underline on only the MouseEnter event.
Private Overloads Sub OnMouseEnter(ByVal sender As Object, ByVal e As EventArgs)