[ExtJs] - Update Panel Data

== updating panel ==
panel1 = new Ext.Panel({
html: 'panel one'
});
panel2 = new Ext.Panel({
html: 'panel two'
});

== default panel ==
fitpanel = new Ext.Panel({
layout:'fit',
region: 'center'
});

=== change option ==
fitpanel.remove(panel1, true);
panel2 = new Ext.Panel({
html: 'panel two'
});
fitpanel.add(panel2);
fitpanel.doLayout();