There is a lot of JavaScript included on this page, but most of it is included simply to show the query string alerts. You can make this widget work by inluding: 'yahoo-dom-event.js', 'core.js', 'array.js', 'Checkbox.js' (you will need to replace all instances of "Object.is(o)" with "isType(o, 'object')" if you don't also include 'object.js')

Shows a 3-state checkbox that becomes a 2-state checkbox once clicked.

Shows a 3-state checkbox, you must press the button to render.

Shows the default checkbox.