Have you configured your desktop shortcut to disable the runtime or something?
I do notice your runtime is behind by about a month, would you update your system via update manager and retest.
Attached is the contents of my steam.desktop file, in case that's wrong. I've never edited it, but this is the shortcut I use to launch steam.
Also, my system reports that it is entirely up to date through update-manager, even if I press the "check" button. I'm still having the problem, and Steam's overlay still only loads if I start steam via a terminal.
[Desktop Entry]
Name=Steam
Comment=Application for managing and playing games on Steam
Exec=/usr/bin/steam %U
Icon=steam
Terminal=false
Type=Application
Categories=Network;FileTransfer;Game;
MimeType=x-scheme-handler/steam;
Actions=Store;Community;Library;Servers;Screenshots;News;Settings;BigPicture;Friends;
[Desktop Action Store]
Name=Store
Name[de]=Shop
Name[es]=Tienda
Name[fr]=Magasin
Name[it]=Negozio
Name[pt]=Loja
Name[ru]=Магазин
Name[zh_CN]=商店
Name[zh_TW]=商店
Exec=steam steam://store
[Desktop Action Community]
Name=Community
Name[es]=Comunidad
Name[fr]=Communauté
Name[it]=Comunità
Name[pt]=Comunidade
Name[ru]=Сообщество
Name[zh_CN]=社区
Name[zh_TW]=社群
Exec=steam steam://url/SteamIDControlPage
[Desktop Action Library]
Name=Library
Name[de]=Bibliothek
Name[es]=Biblioteca
Name[fr]=Bibliothèque
Name[it]=Libreria
Name[pt]=Biblioteca
Name[ru]=Библиотека
Name[zh_CN]=库
Name[zh_TW]=遊戲庫
Exec=steam steam://open/games
[Desktop Action Servers]
Name=Servers
Name[de]=Server
Name[es]=Servidores
Name[fr]=Serveurs
Name[it]=Server
Name[pt]=Servidores
Name[ru]=Серверы
Name[zh_CN]=服务器
Name[zh_TW]=伺服器
Exec=steam steam://open/servers
[Desktop Action Screenshots]
Name=Screenshots
Name[es]=Capturas
Name[fr]=Captures d'écran
Name[it]=Screenshot
Name[ru]=Скриншоты
Name[zh_CN]=截图
Name[zh_TW]=螢幕擷圖
Exec=steam steam://open/screenshots
[Desktop Action News]
Name=News
Name[de]=Neuigkeiten
Name[es]=Noticias
Name[fr]=Actualités
Name[it]=Notizie
Name[pt]=Notícias
Name[ru]=Новости
Name[zh_CN]=新闻
Name[zh_TW]=新聞
Exec=steam steam://open/news
[Desktop Action Settings]
Name=Settings
Name[de]=Einstellungen
Name[es]=Parámetros
Name[fr]=Paramètres
Name[it]=Impostazioni
Name[pt]=Configurações
Name[ru]=Настройки
Name[zh_CN]=设置
Name[zh_TW]=設定
Exec=steam steam://open/settings
[Desktop Action BigPicture]
Name=Big Picture
Exec=steam steam://open/bigpicture
[Desktop Action Friends]
Name=Friends
Name[de]=Freunde
Name[es]=Amigos
Name[fr]=Amis
Name[it]=Amici
Name[pt]=Amigos
Name[ru]=Друзья
Name[zh_CN]=好友
Name[zh_TW]=好友
Exec=steam steam://open/friends
I don't see a difference and I'm not sure why there would be one. Do you change any environment settings in your terminals?
I haven't modified my environment in terminal or anywhere else. At least not manually. I tend to tinker and meddle with my packages sometimes, and I suppose that that could have caused the issue.
However, upon trying out the newest build of Steam (I updated a while back but haven't gone back to launching it from the icon in a while) it seems to be working again. Not sure what was the problem or why it was fixed, but my issue isn't present anymore.
Thanks all.
Nothing extracted yet.
I've been waiting a couple of days before reporting this because I wanted to make sure it was consistent. But, for about a week now, the Steam Overlay won't show up in a game if Steam is started from the desktop icon or the menu item. There is a workaround where the overlay does work if Steam is started by typing "steam" at a terminal. I'm not sure why these two cases should be different, but they are.
Using ubuntu 12.04 LTS on a Lenovo G780 laptop.