This tutorial will show you how to use the drag'n'drop functions of
PHP-Gtk and go deep into the topic "Files and DnD", as this is not
as trivial as it might look.
In the tutorial we will exemplarily build an application which has
only one widget, a tree. This tree can be filled with branches and
leaves by dropping files over it. You will be able to drag those
files back to different programs, at least if you are not on Windows.
Short: We build a bookmark manager for files.