function Checkbox(_frame, _text, _checked) {
var $outer = this;

// Status of checkbox
var checked = (_checked !== undefined)? _checked : false;

if(!(_frame instanceof Window || _frame instanceof Frame)) {
throw "Checkbox parent element must be a Window or Frame";
}

// Frame containing all checkbox-related components
var frame = new Frame();
_frame.appendChild(frame);

// Used to draw the visual checked "state" of the checkbox
var canvas = new Canvas();
canvas.width = 15;
canvas.height = 15;
frame.appendChild(canvas);

// When the checkbox is clicked, change the status and redraw it
canvas.onClick = function() {
$outer.checked = !checked; // Set checked via the public setter
draw();
};

// Text object to display to the left of the checkable area.
var text = new Text();
text.data = _text;
text.anchorStyle = "topLeft";
text.hOffset = 20;
frame.appendChild(text);

// Ensure that clicking the text associated with a checkbox changes the state too
text.onClick = function() {
canvas.onClick();
};

// Context for the canvas
var ctx = canvas.getContext("2d");

// This is called each time you need to update the checkbox's state
function draw() {
/* We don't need to clear the context each time because the
* checkbox doesn't draw any transparent parts. If there
* were, we'd have to clear the context each time otherwise
* the transparent parts would start to become more opaque
* with each redraw.
*/

var width = canvas.width;
var height = canvas.height;

// Draw border
ctx.fillStyle = "#000000"; // border color
ctx.fillRect(0,0,width,height);

// Paint the background
ctx.fillStyle = "#f0f0f0"; // background color
ctx.fillRect(1,1,width-2,height-2);

// Draw "check" inside of box, if we're supposed to
if(checked) {
ctx.beginPath();
ctx.moveTo(width/4,height/2);
ctx.lineTo(2*width/5,height-height/4);
ctx.lineTo(width-width/4,height/4);
ctx.stroke();
ctx.closePath();
}
}
draw();

// Defines a "getter" which is called each time a user tries to get the value of the public property "hOffset"
this.__defineGetter__("hOffset", function() {
return frame.hOffset;
});

// Defines a "setter" which is called each time a user tries to set the value of the public property "hOffset"
this.__defineSetter__("hOffset", function(value) {
frame.hOffset = value;
});

this.__defineGetter__("vOffset", function() {
return frame.vOffset;
});
this.__defineSetter__("vOffset", function(value) {
frame.vOffset = value;
});

this.__defineGetter__("checked", function() {
return checked;
});
this.__defineSetter__("checked", function(value) {
// Convert inputs to booleans, null/undefined -> false, etc.
checked = Boolean(value);
draw();
});

// Make the text property public, so we can use it to identify this checkbox later.
this.__defineGetter__("label", function() {
return text.data;
});
this.__defineGetter__("label", function(value) {
text.data = value;
});
}