Setting environment variables at X login

I've been asked how to set a variable after gdm has done login. ~/.bashrc is not an option, as it's only run by shells, but we want the variable to be set in every X application that is started.

The answer is:

• ~/.profile for text and graphical sessions
• ~/.xprofile for graphical sessions only

Forget about ~/.xinitrc. ~/.xsession and ~/.Xsession: at least in gnome-session, they do not work.

Update: * On IRC, I've been told that ~/.xsessionrc should be used since xorg 1:7.3+9