I convert <selects>-s to Ext.comboboxes im my project.

Thince beta 1 I get an additional field with name "" submitted with the form.
There was one line added to the source in beta 1:

// prevent input submission
this.el.dom.name = '';

(Combo.js, Line 117)

At last in FF this does NOT prevent submission!
As a result I have this empty-named field the server can't handle.