在终端中输入两个命令

gsettings set org.gnome.gedit.preferences.encodings auto-detected "['GB18030', 'GB2312', 'GBK', 'UTF-8', 'BIG5', 'CURRENT', 'UTF-16']"gsettings set org.gnome.gedit.preferences.encodings shown-in-menu "['GB18030', 'GB2312', 'GBK', 'UTF-8', 'BIG5', 'CURRENT', 'UTF-16']"

转自：http://forum.ubuntu.org.cn/viewtopic.php?f=48&t=380247