You can use the template config (tpl) to define how you want the dropdown list to look visually (which is exactly what the following code does in the example that you linked to from your forum post):
var resultTpl = new Ext.XTemplate(
'<tpl for="."><div class="search-item">',
'<h3><span>{lastPost:date("M j, Y")}<br />by {author}</span>{title}</h3>',
'{excerpt}',
'</div></tpl>'
);
....
tpl: resultTpl
You can configure a standard combo box however you want (with or without a dropdown button -- that example uses hideTrigger:true to hide it). Sounds like you would also want triggerAction: 'all' so that the entire list is shown when you click the dropdown button.
Basically, just make sure you look at the ComboBox API docs to see what all is available -- what you want is perfectly standard behavior.