Extjs toggle slide effects

After re-writing the sench touch fieldset to make it collapsible, still I need to add the animation effects to ‘slider up’. the principle of giving the animation effects is pretty simple. by using ‘setInterval’ or ‘setTimeout’ to change the div’s height in certain duration time. in sencha touch api, there is no such a logic to acheive this animation. but I believe in extjs, there should be option to control the animation effects.

Here is the sequence diagrams of collapse animation effects:

it is a little bit complicated because it would be re-used globally. I would rather to write my own instead to find a way to transfer the similar logic to sencha touch.