They're not coming from the server, but directly from the apps running on the user session. Since the login manager is starting the user session, it could be possible to route stderr to some external app for adding the timestamps..
** Changed in: xorg-server (Ubuntu) Status: New => Invalid ** Package changed: xorg-server (Ubuntu) => lightdm (Ubuntu) ** Changed in: lightdm (Ubuntu) Status: Invalid => New -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1088343 Title: please timestamp entries in .xsession-errors Status in “lightdm” package in Ubuntu: New Bug description: Please timestamp log entries made into ~/.xsession-errors, this is very important information. References: bug 285787 http://lists.debian.org/debian-policy/2010/08/msg00043.html To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1088343/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp