Assume that I am visiting a folder (directory) on my system by
M-x dired in Emacs. Also assume that I am visiting a webpage like http://www.gnu.org/software/emacs/manual/pdf/ by the default web browser of my system (say Mozilla Firefox). If I drag the link
elisp.pdf from this webpage and drop it on that dired buffer, the most natural things that one wishes to happen is to save the file
elisp.pdf in that folder.
What are the most natural way to achieve this in Emacs?