I added some new features to the visual designer I mentioned a few days ago. Now there is automatic synchronization from the view to the source (not yet from the source to the view), as well as better checking about where the drop can take place, i.e., the "logo" can only be in the header, etc, as well as a drop image, if the item can be dropped.
Video speaks better than words:
Even though it's got HTML in the name, it's simply a visual designer for XML files. After that, the idea is that the XML files get converted to HTML.