[SOLVED] Current Where Tab ID

I'm attempting to use the "Additional Where Tabs" functionality but I would like to control what's displayed depending on the tab selected. For example, I would like to show the "Add new" button only if the "Where Tab ID" == 0 and hide it otherwise or show/hide fields if the "Where Tab ID" != 0.

My main question is how do I obtain the active tab? I tried the following but I guess this only works for tabs made in Designer?

var tabs = pageObj.getTabs();
var idx = tabs.activeIdx()


var id = "addButton";
var button = $("[id^=" + id + "]");
if (idx != 0){
button.hide();
}

var tabs = pageObj.getTabs();
var idx = WhereTabs.activeIdx()


var id = "addButton";
var button = $("[id^=" + id + "]");
if (idx != 0){
button.hide();
}