here is a simple plugin that will change any panel into a form. The usefulness of this is to avoid unnecessary level of nesting. Pseudo code on how you can use this:
Code:
var p = new Ext.TabPanel({
	plugins	: 'form',
	items	: [{
		... // form 1
	}, {
		... // form 2
	}]
});
...
var form = p.getForm();
The plugin itself:
Code:
Ext.ns('Ext.ux');
/**
 * Simple plugin that will turn any plugin into a form
 * this helps to avoid unneeded level of nesting
 * 
 * @author Albert Varaksin
 * @version 1.0
 * @extends Object
 */
Ext.ux.FormPlugin = Ext.extend(Object, {
	
	/**
	 * Initalize the plgugin
	 * 
	 * @param {Ext.Panel} p
	 */
	init : function(p) {
		// basic form		
		var f = this._form = new Ext.form.BasicForm(null, {});
		// init the <form> element
		if (!p.rendered) {
			p.on('render', function() {f.initEl(p.body)});
		} else {
			f.initEl(p.body);
		}
		// apply the fields
		var isField = Ext.form.FormPanel.prototype.isField;
		var fn = function(c) {
			if(isField(c)){
				f.add(c);
			}else if(c.findBy && c != p){
				//each check required for check/radio groups.
				if(c.items && c.items.each){
					c.items.each(fn, this);
				}
			}
		};
		p.items.each(fn, this);
		// apply data to the panel
		Ext.apply(p, {
			bodyCfg	: {
				tag		: 'form'
			},
			_form	: f,
			getForm	: function() { return this._form; }
		});
		// destroy
		p.on('destroy', this.onDestroy, this);
	},
	
	/**
	 * Called apon destruction
	 */
	onDestroy : function() {
		this._form.destroy();
		delete this._form;
	}
});
Ext.preg('form', Ext.ux.FormPlugin);