I have an advanced search form with three checkboxes properties, when I check just one of this property the results are of documents that has only the checked property. Is possibly to make a form that can search for all documents with one checked property, but not excluding the documents with others unchecked properties?
Thanks for your answer, I try your solution and the behavior is working as need. But the options "true", "false" and "" are not that intuitive in my native language (Portuguese), there is a way to use other words in the droplist, like a key-value?
Those are just the values to be used in the backend. As you can see in the documentation for forms, a select list (selectone.ftl / selectmany.ftl) can contain localised display labels in its "options" parameter.