Question: When I use different layouts to support different screens , should I use dp or px .

Answer: 
Use the jQueryUI version of `toggle()` since you seem to be using a jQuery UI effect

**.toggle( effect [, options ] [, duration ] [, complete ] )**

Reference: <http://api.jqueryui.com/toggle/>

```
$(".fold_reply").click(function() {
     $(".reply").toggle("fold",  500);
})

```
```
$(".fold_reply").click(function() { 
     var style=$('.reply').css('display');
    if (style=='none') {
        $(".reply").show(500);
    }
    else {
        $(".reply").hide(500);
    }

});​

<input type="button" class='fold_reply' value="button">

<div class='reply'>
    text<br/>text<br/>text<br/>text<br/>text
</div>​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

```

**[Working Demo](http://jsfiddle.net/DQvZT/)**