Thank you very much @Scott for your answer. With your help I successfully upgraded all of the old icons that were inputs before, to new <button> versions of them.
The Material Design theme development is afoot again and will be available for download very soon.
In case anyone is wondering how I did it, here's the code I added to my template (qa-theme.php) to make the changes.
public function notice($notice){
$this->output('<div class="qa-notice" id="'.$notice['id'].'">');
if (isset($notice['form_tags']))
$this->output('<form '.$notice['form_tags'].'>');
$this->output_raw($notice['content']);
$this->output('<button '.$notice['close_tags'].' type="submit" value="X" class="qa-notice-close-button"></button>');
if (isset($notice['form_tags'])) {
$this->form_hidden_elements(@$notice['form_hidden']);
$this->output('</form>');
}
$this->output('</div>');
}
public function search_button($search){
$this->output('<button type="submit" value="'.$search['button_label'].'" class="qa-search-button"></button>');
}
public function favorite_button($tags, $class){
if (isset($tags))
$this->output('<button '.$tags.' type="submit" value="" class="'.$class.'-button"></button> ');
}
public function form_button_data($button, $key, $style){
$baseclass = 'qa-form-'.$style.'-button qa-form-'.$style.'-button-'.$key;
$this->output('<button'.rtrim(' '.@$button['tags']).' value="'.@$button['label'].'" title="'.@$button['popup'].'" type="submit"'.
(isset($style) ? (' class="'.$baseclass.'"') : '').'>'.@$button['label'].'</button>');
}
public function post_hover_button($post, $element, $value, $class){
if (isset($post[$element]))
$this->output('<button '.$post[$element].' type="submit" value="'.$value.'" class="'.$class.'-button"></button>');
}
public function post_disabled_button($post, $element, $value, $class){
if (isset($post[$element]))
$this->output('<button '.$post[$element].' type="submit" value="'.$value.'" class="'.$class.'-disabled" disabled="disabled"></button>');
}
All of the changes in the code above were targeted only for inputs of the type submit. I'll try to keep this post up to date in case I find any bugs, or missing buttons while developing the theme.