It is impossible to do this without a corehack.
1. Locate function qa_question_set_selchildid in file qa-app-post-update.php
2. Locate this line inside that function:
$oldselchildid=$oldquestion['selchildid'];
3. Immediately BEFORE add the following code:
// CORE HACK: Prevent users to select own answers
if ($answers[$selchildid]['userid'] == $oldquestion['userid']) {
return;
}
4. Play around your site and try to select an answer posted by the question creator. You shouldn't.
5. In order to make the select mark go away, go to /qa-theme/<your-theme>/qa-theme.php
6. Locate the doctype() function
6.1 If it is not there add this function to the file the same as any other function there:
function doctype() {
qa_html_theme_base::doctype();
if ($this->template === 'question' &&
isset(
$this->content['q_view']['raw']['userid'],
$this->content['a_list']['as']
) && !empty($this->content['q_view']['raw']['userid'])
) {
$questionCreator = $this->content['q_view']['raw']['userid'];
$answerList = $this->content['a_list']['as'];
foreach ($answerList as $index => $answer) {
if (isset($answer['raw']['userid']) &&
$answer['raw']['userid'] == $questionCreator
) {
unset(
$this->content['a_list']['as'][$index]['select_tags'],
$this->content['a_list']['as'][$index]['select_text']
);
}
}
}
}
6.2 If it is, there take the code from 6.1 and everything between qa_html_theme_base::doctype(); and the last } (excluding both of those lines) and add that immediately after the function doctype() { in your already existing function
7. Enjoy