Widget: Open in new window

I have a custom widget that links to an external site (essentially it's a billing system) when the client clicks the link, it takes them off the support suite and onto the external site.

As Widgets used to be controllable through an unencrypted widgets.php I could put target="_blank" into the link to allow it to be opened within a new window/tab.

I can't seem to find any way to replicate this through the new Widgets module in the...

Widget: Open in new window