Sorry, that didn't did the trick either.
OK, from scratch
Base Template code
<html>
<head>
<title>[[*pagetitle]]|[[++site_name]]</title>
<base href="[[++site_url]]" />
</head>
<body>
[[*content]]
</body>
</html>
index.php?id=5 page code
<p>Enter a name</p>
[[!GetArtist?&landing='5']]
Snippet code with the name GetArtist
$docId = $modx->getOption('landing',$scriptProperties,$modx->resource->get('id'));
$url = $modx->makeUrl($docId, "", "", "full");
return $output = '<form name="form" action="' . $url . '" method="get"><input type="text" value="Rembrandt" name="q" />
<input type="submit" name="Submit" value="Search" /></form>';
When I use the Base Template it is strange that the part
from the index.php?id=5 page isn't displayed.
I'm a little bit desperate I can't tackel this one. My php, html or jscript skills are above mediocre so that is not the problem. I understand what I'm doing but at the moment I'm in a dead end.
Perhaps somebody can give me a link to a working form in Modx with just plain html without things like Chuncks, Snippets, PHP etc so I can take that as a starting point.