I'm new to using RichFaces, and couldn't find an answer to this in my searches, so please forgive me if this has been covered somewhere and I missed it.

I'm trying to send parameters to a richfaces effect function on the fly using javascript functions.  I currently have a javascript function that resizes a DIV, and keeps track of a variable that remembers what the current size is, so that when the user wants to enlarge/shrink the box, it knows what size to make it.   Right now it works, but I'd like to improve the asthetics by using the Morph effect.  Here's a simplified version of how I'm doing it now:

...

function enlargeDiv(){
    divWidth = divWidth + 100;   
    document.getElementById("myDiv").style.width = divWidth;

}

...

I can morph the box using richfaces effects, but I can't figure out how to do it when the width will keep changing.  I know how to call the effect from a javascript function if all the params are defined in the richfaces code like this:

<rich:effect name="resizeDiv" for="myDiv" type="Morph" params="style:'width:500px',duration:0.8" />

But I can't figure out how to put those params in the javascript function call.  Or better yet, is there a way to tell the richfaces call to increase/decrease the size by a certain amount, rather than telling it the exact px size?  Something like "params='style:width:+100px"?

Any ideas?

Thanks