Ironically I just learned how to do this over the weekend and was going to post this someplace as a tip.
You need to create a plug-in that can set this for you (actually plug-ins can be used to set default settings in most of the manager options with a little creativity).
Here is what you do:
1) find the id of the group or groups that you want to have selected. To do this I looked at the source of the "create web user" form and looked at the values for the check boxes.
2) create a new plug-in and paste the following into it:
// set the default web doc group to intranet
// event set to OnWUsrFormPrerender
// put the id for the usergroup in the array bellow seperated by a comma
if($_GET['a'] =='87') {
$_POST['user_groups'] = array(1,2,3);
}
3) edit the array ’array(1,2,3)’ to include the ids for the groups you want to set. If the group is 19 it would read as array(19).
4) In the plug-in events select the OnWUsrFormPrerender check box.
5) save and test. If it worked correctly the check boxes for the corresponding groups should be set.
Note: this is only active for creating new users, when editing existing users this will not change the settings. The if statement checks to see if it is a new user or editing an existing one: if($_GET[’a’] ==’87’)
This should do it. Works for me like a charm.
PS: you may also like to change the useless politically incorrect "Gender" column in the webuser list to show the number of logins instead. To do so check out this other post (warning this requires hacking files):
http://modxcms.com/forums/index.php/topic,23945.msg147463.html#msg147463
