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.

When the user double clicks on a key, the corresponding value will be added
in the HList.

If the value is a multi-line scalar, the scalar will be displayed in a
popup text window. Code ref will be deparsed and shown also in the pop-up
window.

Tied scalar, hash or array internal can also be scanned by clicking on the
_middle_ button to open them.

Weak references are recognized (See the WeakRef manpage for details)