 Check if the definition is from the dialog we're
			// interested on (the "Link" dialog).
			if ( dialogName == 'myDialog' && ev.editor.name == 'editor2' ) {
				// Get a reference to the "Link Info" tab.
				var infoTab = dialogDefinition.getContents( 'tab1' );

				// Add a new text field to the "tab1" tab page.
				infoTab.add( {
					type: 'text',
					label: 'My Custom Field',
					id: 'customField',
					'default': 'Sample!',
					validate: function() {
						if ( ( /\d/ ).test( this.get