public boolean isLoaded(int index) {
        Object value = getStateHelper().get("loaded_" + index);
        return Boolean.TRUE.equals(value);
    }
In case of a repeating parent (var=...), we need to store the state on row basis.
This is actually a workaround because neither UITabPanel, not UIRepeat has a rowStatePreserved attribute.

@param index The tab index.
@return if loaded or not.
primefaces/src/main/java/org/primefaces/component/tabview/Tab.java