The DocBook 5 extensions are the same as the DocBook 4 extensions. In addition the table actions work also for HTML tables.
A drag and drop with a file from the
Project view or from the DITA Maps
Manager view to a DocBook 5 document that is edited in Author mode will
create a link to the dragged file (the link DocBook element) at the drop
location. A drag and drop with an image file from the default file system application (Windows
Explorer on Windows, Finder on Mac OS X, etc) will insert an image element (the
inlinemediaobject DocBook element with an imagedata child
element) with the location of the dragged file at the drop location, like the
Insert Graphic toolbar action.