itemconfigure

Tcl/Tk

#!/usr/local/bin/wish4.2

canvas .canvas
.canvas create rectangle 1c 2c 3c 3c \
		-outline black -fill blue -tags rect
pack .canvas

bind .canvas <Enter> {.canvas itemconfigure rect -fill red}
bind .canvas <Leave> {.canvas itemconfigure rect -fill green}

ruby/Tk

#!/usr/local/bin/ruby

require "tk"

canvas = TkCanvas.new
grp = TkcGroup.new(canvas)
grp.add(TkcRectangle.new(canvas, '1c', '2c', '3c', '3c',
				 'outline' => 'black', 'fill' => 'blue'))
canvas.pack

canvas.bind 'Enter' do
  grp.configure 'fill', 'red'
end
canvas.bind 'Leave' do
  grp.configure 'fill', 'green'
end

Tk.mainloop