-is dragable. If nothing is given then the whole child element is
-dragable, and clicks through to underlying elements like inputs or
-links might not work.
+is dragable. If the parameter is not given then it defaults to
+C<.dragdrop> matching DOM elements with the class C<dragdrop>. If the
+parameter is set and empty then the whole child element is dragable,
+and clicks through to underlying elements like inputs or links might
+not work.