The following code was extracted from Core_DoJoEffect.xsp.
The duration attribute for <xe:dojoFadeOut> tag should be 2000, but it is 200 now.
<xp:button value="Fade Out - Duration 2s" id="button3">
<xp:eventHandler event="onclick" submit="false">
<xp:this.script>
<xe:dojoFadeOut node="effect1" duration="200">
</xe:dojoFadeOut>
</xp:this.script>
</xp:eventHandler>
</xp:button>