Inventions on Drag and Drop in GUI
  Drag and drop operation is one of the key capabilities of any Graphical User Interface. The user can do quite complex operations simply by visually dragging and dropping objects from one location to another. It saves user from remembering and typing a lot of commands.   The result of a drag and drop operation may vary depending the type of source object and type of destination object. For example dragging a file and dropping on a folder may copy or move the file to the destination folder, dropping that file to a remote FTP location may upload that file using internet, dropping that file on a printer icon may print that file, dropping that file on the trash can may delete that file, and dropping that file on an executable may play or open or compute or manipulate that file.   Although a drag and drop operation prima facie seems to be a simple operation, it can become extremely complicated depending on the type of source objects dragged and the type of destination objects selected for dropping. There are many limitations of a conventional drag and drop operation. This article points out the difficulties of a drag and drop operation and illustrates the solutions disclosed by various inventions to overcome those difficulties. 
Umakant Mishra
cs.HC