Shoutbox

Its all in the first few lines of the 923 definition.

<element layout=borderlayout() padding=rect(0,0,1,0)>
        <Element id=atom(tabseparator) layout=filllayout()>
            <Element layout=filllayout() borderthickness=rect(0,1,0,0) ID=Atom(ai196)>
                <Element padding=rect(0,0,0,0) layout=filllayout() borderthickness=rect(0,1,0,0) ID=Atom(ai197)/>
            </Element>
        </Element>
    </element>

Just change them to borderthickness=rect(0,0,0,0) and voila done