[jQuery] UI/Resizable

hi
I applied the resize option to resize a textarea's height while the
width should be dynamic (100%), so if the user resizes the browser
window the textarea changes it's size.
The default behavior seams to be that the width changes to a fixed
value. Anyone an idea how to change that?
thanks for any hints
$(".resize-y").resizable({
handles: "s,e",
preventDefault: true
});
nos