In order to make elements styled after updatepanel is updated, we just need to call myform_manager.refresh() inside OnUpdatePanel event of KoolAjax's UpdatePanel.
<?php
require $KoolControlsFolder."/KoolAjax/koolajax.php";
require $KoolControlsFolder."/KoolGrid/koolgrid.php";
require $KoolControlsFolder."/KoolForm/koolform.php";
$koolajax->scriptFolder = $KoolControlsFolder."/KoolAjax";
$myform_manager = new KoolForm("myform");
$myform_manager->scriptFolder = $KoolControlsFolder."/KoolForm";
$myform_manager->DecorationEnabled = true;
$myform_manager->styleFolder = "sunset";
$myform_manager->Init();
?>
<form id="myform" method="post">
<style type="text/css">
.panel_class
{
width:230px;
}
</style>
<?php echo $koolajax->Render();?>
<?php echo KoolScripting::Start()?>
<updatepanel id="myupdatepanel" class="panel_class">
<content>
<fieldset style="width:200px;padding-bottom:10px;padding-left:5px;" class="decoration">
<legend>UpdatePanel</legend>
<div style="height:5px;"></div>
<input id="chk1" name="chk1" type="checkbox" /><label for="chk1">Football</label>
<br />
<input id="chk2" name="chk1" type="checkbox" /><label for="chk2">Basketball</label>
<br />
<input id="chk3" name="chk1" type="checkbox" /><label for="chk3">Volleyball</label>
<br /><br/>
<input id="btnSubmit" type="submit" value="Submit" />
</fieldset>
</content>
<loading image="<?php echo $KoolControlsFolder;?>/KoolAjax/loading/5.gif"/>
</updatepanel>
<?php echo KoolScripting::End()?>
<?php echo $myform_manager->Render();?>
<script type="text/javascript">
myupdatepanel.registerEvent("OnUpdatePanel",function(sender,args){
myform_manager.refresh();
});
</script>
</form>
KoolForm FullVersion 1.8.0.2 released on 25/11/2016