function AddImage(weburl, image, textarea)
{
url = '<a class="thickbox" href="'+weburl+'media/image/'+image+'"><img class="gal_img" src="'+weburl+'media/thumb/'+image+'"></a>';
textarea.value += url;
textarea.focus(textarea.value.length - 1);
}<a href="javascript:AddImage('http://127.0.0.1/','B-Bonsai.png', content)"><img class="gal_img" src="http://127.0.0.1/media/thumb/B-Bonsai.png"></a>