Primefaces: how to change the default icon on the button of the calendar field?

Question

In Primefaces, how do I change the icon that is being used by the button of the calendar field?

For example, in the following field

<p:calendar value="#{calendarBean.date3}" id="popupButtonCal" showOn="button" />

I want to change the icon to http://forum.primefaces.org/images/smilies/icon_e_wink.gif.

I've looked at the documentation, but I cannot find an attribute for this.

UPDATE:

I have tried the following, with partial success:

JSF:

<p:commandButton id="modalDialogButton" value="" onclick="dlg2.show();" type="button" icon="ui-calendar"/>

CSS:

.ui-widget .ui-calendar {

    background-image: url(#{resource['images:country_flag.gif']});
}

PROBLEMS:

1. I do see the image on the p:commandButton button now. But, I am getting the warning message:

   Apr 03, 2012 10:43:58 AM com.sun.faces.application.resource.ResourceHandlerImpl logMissingResource WARNING: JSF1064: Unable to find or serve resource, images/country_flag.gif.jsf.

2. I could not find a css style on the p:calendar that I should override in order to change the image on the calendar button.

Solution

try this

.ui-icon-calendar {
    background-image: <your URL> !important;
    background-position: center center !important;
    width: 16px;
    height: 16px;
}