Add "Are you sure you want to navigate away from this page?"

Add the standard "Are you sure you want to navigate away from this page? You have not saved your changes."

When, in the middle of creating a new resource, i click something in the tree by accident, or accidentally lift my finger off the mouse-button while dragging the parent resource into the parent field, then the page nav’s to the item in the tree i clicked on, and i lose all my edits to the new resource.