gistfile1.js

document.observe("dom:loaded", function() {


	var customsPage = Class.create({
		initialize: function(page, draggable_obj) {
			
			if(draggable_obj)
				this.draggableObject = new Draggable(draggable_obj);
			
			Object.extend(page, this);
		},

		deactivate_draggable: function() {
			if(this.draggableObject)
				Draggables.unregister(this.draggableObject);
		}

	});
	
	
	$$('.customizations_page').each(function(page) {

		var object_to_drag = null;
		
		switch(page.readAttribute("id")) {
			case "pagetitle":
				object_to_drag = $$("#header h1").first();
				break;
		}
		
		new customsPage(page, object_to_drag);
		
		
		
		page.observe("layout:show", function(event) {

			var last_active_page = $$('#customizations_menu li.active').first();
			
			this.deactivate_draggable();			// works like a charm
			last_active_page.deactivate_draggable();	// fails. TypeError: Result of expression 'last_active_page.deactivate_draggable' [undefined] is not a function.
		});
	});
});