http://www.bin-co.com/tcl/tutorial/widgets6.php
canvas .cns -relief sunken -background "blue"
.cns create polygon 5 100 50 5 150 5 200 100 5 100 \
-joinstyle bevel -fill "red" -outline "white" -width 5
.cns create oval 200 100 300 200 -fill "green"
.cns create oval 100 150 300 100 -fill "white" -width 0
.cns create rectangle 10 150 100 250 -dash {6 4 2 4 2 4}
pack .cns