Simple question about Task( )

I'm trying to animate a change in a [panel]'s presentation_rect. After some reading and experimentation, I figured the Task() object would be the most appropriate way to go. But I'm having trouble changing the arguments...

var tsk;
var args;

function init() {
        args = new Array();
    args[0] = "tick";
    tsk = new Task(dummy, this, args);
    tsk.interval = 1000;
    tsk.repeat(4);
}

function dummy(s) {
    if(s=="tick") args[0] = "tock";
    if(s=="tock") args[0] = "tick";
    post(args[0]);
}

It seems that args[0] always contains "tick" and never a "tock". As if the initialization of Task() takes in the values of args[] upon creation, instead of checking the pointer during each interval. Or am I missing something?

Either way, i'd like to know how to get around this, or some other scripting method I could use to delay a change in an object's attributes. Any thoughts?