Navigation tree builder

Now if you want to link an element to another mockup you have first to create your destination, and then go back to the source mockup and add the link.

One possible solution to solve this pain is to add a <new> item in the link dropdown.

Another would be to introduce the concept of a "project" file, that links together many mockups. This way you could design the navigation of the "application", with the various steps and screens, before you actually start designing the mockups</new>