Position a textbox over the top of the canvas element using absolute positioning.
my suggested layout is something like:
<div style="position:relative;width:800px;height:800px"> <canvas width="800" height="800"></canvas> <input type="text" style="position:absolute;left:100px;top:300px;width:600px; etc...." /> </div>
with this you have the relative positioned
<div> to base where your going to pop things up over, I would probably also add a modal backdrop...
hope this helps -ck