When I used the setDefaults() method in QuickForm to set the selected option in a selectbox I get this HTML code:
<option [...] 0="selected"> and the options doesn't get selected.

The following code in toHTML (in select.php) seems wrong:

            foreach ($this->_options as $option) {
                if (is_array($this->_values) && in_array($option['attr']['value'], $this->_values)) {
                    $this->_updateAttrArray($option['attr'], array('selected'));
                }

should be:

            foreach ($this->_options as $option) {
                if (is_array($this->_values) && in_array($option['attr']['value'], $this->_values)) {
                    $this->_updateAttrArray($option['attr'], array('selected' => 'selected'));
                }