If it can help lxdm users I created a /usr/share/xsessions/Xsession.desktop file containing:
[Desktop Entry] Encoding=UTF-8 Name=Xsession Comment=Highly configurable framework window manager TryExec=/etc/X11/Xsession Exec=/etc/X11/Xsession
after that I can select Xsession in lxdm and it runs my custom ~/.xsession file
If it can help lxdm users I created a /usr/share/ xsessions/ Xsession. desktop file containing:
[Desktop Entry] /etc/X11/ Xsession X11/Xsession
Encoding=UTF-8
Name=Xsession
Comment=Highly configurable framework window manager
TryExec=
Exec=/etc/
after that I can select Xsession in lxdm and it runs my custom ~/.xsession file