The scanner provides a GUI to scan the attributes of an object. It can also
be used to scan the elements of a hash or an array.

This widget can be used as a regular widget in a Tk application or can be
used as an autonomous popup widget that will display the content of a data
structure. The latter is like a call to a graphical the Data::Dumper
manpage. The scanner can be used in an autonomous way with the
'scan_object' function.

The scanner is a composite widget made of a menubar and the Tk::HList
manpage. This widget acts as a scanner to the object (or hash ref) passed
with the 'caller' parameter. The scanner will retrieve all keys of the
hash/object and insert them in the HList.