require 'tkmove3.rb'
include TestBed

c = TkCanvas.new.pack
testbed( c )

f = TkFrame.new.pack
TkButton.new(f, 'text'=>'addtag_below', 'command'=>proc{
  c.bind('B1-Motion', proc{})
  c.bind('1', proc{
    item = c.find_withtag('current').shift
    c.addtag_below( 'below', item )
    item = c.find_withtag('below').shift
    if item != nil
      item.fill('blue')
    end
    c.dtag('below')
  })
}).pack('side'=>'left')

Tk.mainloop