You can select a new default skin for a site via two following ways:
Directly inline, via the UI of eXo Platform. See the Editing configurations section for more details.
In your extension, via the XML configuration file as below.
The default skin can be set in the portal configuration files. The skin configured as default is used by eXo Platform as the administrator starts/restarts the server.
To change the default skin of a site, for example Intranet, simply add a skin tag to the custom-extension.war!/WEB-INF/myintranet-conf/portal/intranet/portal.xml file.
<portal-config>
<portal-name>intranet</portal-name>
<locale>en</locale>
<access-permissions>Everyone</access-permissions>
<edit-permission>*:/platform/administrators</edit-permission>
<skin>MySkin</skin>
...
</portal-config>