A very generic Views Wizard class - can be constructed for any base table.
Code
protectedfunctiondefault_display_filters($form, $form_state) {
$filters = array();
// Add any filters provided by the plugin.
if (isset($this->plugin['filters'])) {
foreach ($this->plugin['filters'] as$name => $info) {
$filters[$name] = $info;
}
}
// Add any filters specified by the user when filling out the wizard.
$filters = array_merge($filters, $this->default_display_filters_user($form, $form_state));
return$filters;
}