HyperlinkButton is the HyperlinkButton of WinUI for WPF. It is a ButtonBase that looks like a link, for a link that stands on its own: under a form, in a dialog, below a list. The WPF Hyperlink is an inline that only lives inside a TextBlock; the button stands anywhere a button can, takes any content and has Click, Command and the focus of a button.

<mah:HyperlinkButton Content="MahApps.Metro on GitHub" NavigateUri="https://github.com/MahApps/MahApps.Metro" />

Navigating

A click raises Click and runs the Command first. With a NavigateUri it then raises RequestNavigate, which is the very event of the WPF Hyperlink, so a Frame or a NavigationWindow around the button navigates on its own, and any handler can take the URI by setting Handled.

When nobody takes it, an http, https or mailto URI opens in the program Windows has for it. Every other URI, a relative one, a file: one or one of a custom scheme, goes to the handlers alone. WinUI opens every scheme but file:; it does that from a sandbox, and a desktop app has none, so a URI from data the app does not control could start whatever program registered its scheme. An app that wants another scheme opened handles RequestNavigate and decides there. LaunchUri is the method that opens the web and mail URIs and can be overridden, for example to open them in a WebView2 of the app instead.

private void OnRequestNavigate(object sender, RequestNavigateEventArgs e)
{
    if (e.Uri.Scheme == "gallery")
    {
        this.ShowPage(e.Uri.AbsolutePath);
        e.Handled = true;
    }
}

Without a NavigateUri the button is a plain button: Click and Command, and nothing opens.

The underline

Only text content is underlined, as in WinUI: a string, _Help with its access key included. An element given as content keeps its own look, so an image or a TextBlock of your own gets no line under it.

IsUnderlineVisible switches the underline. The Metro and the Windows 10 look have it on, WinUI has it off, because WinUI sets HyperlinkUnderlineVisible to False and only draws the line in high contrast.

The three looks

Each style set has its own button, and the button follows the set it is in.

The text colours are the ones of the link in the same set: MahApps.Brushes.Hyperlink.Win10.Foreground, .ForegroundPointerOver, .ForegroundPressed and .ForegroundDisabled, and the same four for WinUI. Overriding them colours the inline link and the button alike.

Differences to WinUI

The URI goes through RequestNavigate first, so the app can take it, and only web and mail URIs open by themselves. IsUnderlineVisible is a property rather than a theme resource. The shades of the accent the WinUI look writes in are the ones every theme carries, which match Windows exactly only when the theme follows the Windows accent.

Related

Hyperlink for the link in running text, Win10 and WinUI for the sets.