Alt key doesn't work in Vivid Vervet with Emacs

[Paul Eggert]

Emacs has a handy feature with the Alt key. If I type, say "Control-X 8 ' a", it's as if I typed "á", but once I've started doing that there's a faster way to do it, namely, type "Alt-' a". Unfortunately in Vivid Vervet this doesn't seem to work: every time I type "Alt-'" Emacs acts as if I typed "Meta-'", and similarly "Alt-x" is treated as if I typed "Meta-x", and so on for every character, which means that Alt is essentially useless.

I tried all the methods suggested on the net to work around this, and none of them worked. For example, the shell command 'xmodmap -pm' reports:

xmodmap: up to 4 keys per modifier, (keycodes in parentheses):

shift Shift_L (0x32), Shift_R (0x3e)
lock Caps_Lock (0x42)
control Control_L (0x25), Caps_Lock (0x42), Control_R (0x69)
mod1 Alt_L (0x40), Alt_R (0x6c), Meta_L (0xcd)
mod2 Num_Lock (0x4d)
mod3
mod4 Super_L (0x85), Super_R (0x86), Super_L (0xce), Hyper_L (0xcf)
mod5 ISO_Level3_Shift (0x5c), Mode_switch (0xcb)

but when I type, for example, "xmodmap -e 'clear mod1'", it complains:

X Error of failed request: BadValue (integer parameter out of range for operation)
  Major opcode of failed request: 118 (X_SetModifierMapping)
  Value in failed request: 0x17
  Serial number of failed request: 8
  Current serial number in output stream: 8

Apparently this has something to do with the change to Wayland, which deprecates xmodmap. The Gnome keyboard settings UI doesn't let one change how Alt works. gnome-tweak-tool complains as follows when I try to run it:

$ gnome-tweak-tool
WARNING : Shell not installed or running
WARNING : Error detecting shell
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/gtweak/tweaks/tweak_group_shell_extensions.py", line 278, in __init__
    raise Exception("Shell not running or DBus service not available")
Exception: Shell not running or DBus service not available
WARNING : Shell not running
None
INFO : GSettings missing key org.gnome.nautilus.desktop (key computer-icon-visible)

and if I ignore this and click on "Typing", I get a bunch of seemingly-helpful possibilities, none of which work (and, by the way, the menu choices are often unreadable).

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: emacs (not installed)
ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3
Uname: Linux 3.19.0-15-generic x86_64
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
CurrentDesktop: Unity
Date: Sun May 3 17:10:40 2015
InstallationDate: Installed on 2012-12-21 (863 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
SourcePackage: emacs-defaults
UpgradeStatus: Upgraded to vivid on 2015-04-24 (9 days ago)