The value of a ComboBox is lost if it does not have any options added. A ComboBox is rendered as a select form element, and the decorator removes the value attribute. This is fine when there are options and an option matches the value. But in a ComboBox with no options the value should be preserved in the input tag. This is important to keep because the ComboBox's options may be filled later with a datastore.

The following should make a ComboBox with "test" as its value.

$form = new Zend_Dojo_Form();
$combo = $form->createElement('ComboBox', 'combo');
$combo->setValue('Test');
$form->addElement($combo);