Retrieves a single property for the defined element type.
$type: An element type as defined by hook_element_info().
$property_name: The property within the element type that should be returned.
$default: (Optional) The value to return if the element type does not specify a value for the property. Defaults to NULL.
function element_info_property($type, $property_name, $default = NULL) {
return ($info = element_info($type)) && array_key_exists($property_name, $info) ? $info[$property_name] : $default;
}