>>617
スクリプトとはちょっと違うかもだけど、custombuttonsでボタンを設置できるよ

中身は↓な感じ
this.clear = function ClearFields_Search()
{
var searchbar = document.getElementById('searchbar');
if (searchbar) {
searchbar.textbox.value = "";
var evt = document.createEvent("Events");
evt.initEvent("oninput", true, true);
searchbar.dispatchEvent(evt);
searchbar.focus();
}
return
}
this.setAttribute("onclick", "this.clear(event);");
this.setAttribute("homepage","http://custombuttons.phpbbnow.com/viewtopic.php?t=24");