externalLinkTarget with Neos.Neos:Menu

I’m wondering why shortcuts to external pages are opened in current tab instead of a new tab.

I’ve got a menu which is built by:

legal = Neos.Neos:Menu {
    itemCollection = ${Array.isEmpty(q(site).property('legal') ? q(site).property('legal') : {}) ? null : q(site).property('legal')}

this is finaly output as:

<nav class="legal">{parts.legal -> f:format.raw()}</nav>

If one of the items is of type Neos.Neos:Shortcut pointing to an external page I would like to open it in a new tab. The menu output is fine, but there is no target="_blank" output.

How can I make this happen?