The release of Liferay 6.2 and AlloyUI 2.0 has brought some changes in the dialogs management, removing some Javascript modules and deprecating other ones. 

Let's see how to handle the following use case with Liferay 6.2: closing a dialog with a button inside the dialog itself.

Open a dialog is a simple operation which, however, requires a minimum of attention; let's suppose to add the opening button in the view.jsp page and to display, inside the dialog, the content of the dialog.jsp page. The procedure is the classical one shown below, with the only particularity to add the id attribute, which uniquely identifies the dialog.

<aui:button name="openDialog" type="button" value="open-dialog" />

<liferay-portlet:renderURL var="dialogURL" windowState="<%=LiferayWindowState.POP_UP.toString() %>">
	<liferay-portlet:param name="mvcPath" value="/dialog.jsp" />
</liferay-portlet:renderURL>
<aui:script use="liferay-util-window">
A.one('#<portlet:namespace/>openDialog').on('click', function(event) {
	Liferay.Util.openWindow({
		dialog: {
			centered: true,
			height: 300,
			modal: true,
			width: 400
		},
		id: '<portlet:namespace/>dialog',
		title: '<liferay-ui:message key="i-am-the-dialog" />',
		uri: '<%=dialogURL %>'
	});
});
</aui:script>

Inside the dialog.jsp page there could be anything (such as a form), but let's suppose that there's a button that trigger some kind of processing (read and manipulate the form fields) and then close the dialog itself.

<aui:button name="closeDialog" type="button" value="close" />

<aui:script use="aui-base">
A.one('#<portlet:namespace/>closeDialog').on('click', function(event) {
	// Let's suppose that "data" contains the processing results
	var data = ...
	// Invoke a function with processgin results and dialog id
	Liferay.Util.getOpener().<portlet:namespace/>closePopup(data, '<portlet:namespace/>dialog');
});
</aui:script>

The getOpener() function returns the window which opened the dialog, namely view.jsp; so the closePopup function must be defined inside view.jsp page.

<aui:script>
Liferay.provide(
	window,
	'<portlet:namespace/>closePopup',
	function(data, dialogId) {
		var A = AUI();
		
		// Here you can use "data" parameter
		
		// Closing the dialog
		var dialog = Liferay.Util.Window.getById(dialogId);
		dialog.destroy();
	},
	['liferay-util-window']
);
</aui:script>