I could find a way how to do it like described above:
1. disable admin option
In admin/viewing/ → uncheck "Show reply button on comments" (or use CSS to hide them)
2. in qa-theme.php you would need:
public function c_list($c_list, $class)
{
qa_html_theme_base::c_list($c_list, $class);
if (!empty($c_list['cs'])) {
// get first element of comment list array
// $firstcomment = reset($c_list['cs']);
// memo: dont take first as this could be the expand tag array (if comments get hidden within "show x comments before")
// get last element of comment list array
$lastcomment = end($c_list['cs']);
$parenttype = qa_db_read_one_value( qa_db_query_sub( 'SELECT `type` FROM ^posts
WHERE `postid` = #', $lastcomment['raw']['parentid']), true );
if(isset($parenttype)) {
$parenttype = strtolower($parenttype);
// default question
$namelink = 'q_docomment';
if($parenttype=='a') {
$namelink = 'a'.$lastcomment['raw']['parentid'].'_docomment';
}
$this->output('
<input name="'.$namelink.'" onclick="return qa_toggle_element(\'c'.$lastcomment['raw']['parentid'].'\')" value="'.qa_lang_html('question/reply_button').'" title="'.qa_lang_html('question/reply_c_popup').'" type="submit" class="qa-form-light-button qa-form-light-button-comment qa-form-light-button-comment-last">
');
}
}
}
3. Add CSS your to qa-styles.css file.
.qa-c-item-buttons .qa-form-light-button-comment {
display:none;
}
.qa-form-light-button-comment-last {
float:right;
margin-top:10px;
padding-bottom:10px;
color:#07C;
font-size:12px;
}
.qa-form-light-button-comment-last:hover {
color:#1075DF;
}
This leads to:
Unfortunately, this needs one more query per comment list... as I cannot get the basetype from $c_list.