You browse the contents of your folder. The selectable items aren't underlined as hyperlinks. Whenever something is selected, the floating window for the inspector is updated with the RDF properties for the currently selected object. Obviously double-clicking follows the item's default action. Currently it is hard to edit.
Chances are it is the target of some other form.
Zope unfortunately gives up on the entire page if one block can't be resolved. In design mode, thought, it should skip over that and just insert something indicating a problem. Perhaps var tags could have defaults to be used while in design mode. Jeffrey espoused an idea yesterday which really floored me. Making them much easier to manage in tools like Dreamweaver.