SYNOPSIS
 use Tk::DropSite qw(...);
 $widget->DropSite(-entercommand => ...,
                   -dropcommand  => ...,
                   -motioncommand  => ...,
                   -dropcommand  => ...,
                  );
DESCRIPTION
"DropSite" creates an object which represents a site on which things may be ``Dropped''.A DropSite provides the following methods:
- $site->Enter($token,$event)
- $site->Leave($token,$event)
- $site->Motion($token,$event)
- $site->Drop($token,$event)
- 

