3.8.3 has changed a little since I remember. I remember not liking how Firefox displayed the textarea within the editor (use of border inset). So I edited the file /clientscript/vbulletin_textedit.js. The structure of the js file has changed but I managed to find what I was looking for. I looked at two areas where inset was found and changed them to (in 3.8.3):
if (!is_ie)
{
this.editbox.style.border = '2px inset';
}
When I add "display:none" to the class .controlbar the entire textarea is removed. When I simply removed the .controlbar I came out with the attachment below. It's probably not what you're looking for. However, it displays the same in IE and Firefox.