alt+tab brutally abruptly produced a "switch user" screen

[Robert D. Martin]

I used alt+tab expecting to therefore switch back and forth from Firefox to Abiword. Instead the switch user screen appeared.

I saw no other way back to the session that I had been using (as user ubuntu) under zevenOS4 than to login again.

Whether it be via xkeyboard-config or otherwise, it would be comforting to be able to change alt+tab to some other, more harmless behaviour.

A suggestion: for the benefit of others, who like myself accidentally use alt+tab for whatever other reason than to purposely invoke the switch user screen, how about adding a window that pop up to ask, say, "Go to 'switch user screen' thus ending the current session J/N"

ProblemType: Crash
DistroRelease: Ubuntu 11.10
Package: lightdm-gtk-greeter 1.0.6-0ubuntu1.1
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic i686
ApportVersion: 1.23-0ubuntu4
Architecture: i386
CasperVersion: 1.287
Date: Thu Jul 25 16:47:43 2013
ExecutablePath: /usr/sbin/lightdm-gtk-greeter
LiveMediaBuild: ZevenOS 4.0 "Oneiric Ocelot" - Release i386 (20111115)
ProcCmdline: /usr/sbin/lightdm-gtk-greeter
ProcEnviron:
 PATH=(custom, no user)
 LANG=de_DE.UTF-8
 SHELL=/bin/false
SegvAnalysis: Skipped: missing required field "Disassembly"
Signal: 11
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:

[Apport retracing service (apport)]

StacktraceTop:
 start_authentication (username=0x0) at lightdm-gtk-greeter.c:149
 g_cclosure_marshal_VOID__VOID (closure=0x8ad53b8, return_value=0x0, n_param_values=1, param_values=0x8c20dc0, invocation_hint=0xbfcba390, marshal_data=0x0) at /build/buildd/glib2.0-2.30.0/./gobject/gmarshal.c:85
 g_closure_invoke (closure=0x8ad53b8, return_value=0x0, n_param_values=1, param_values=0x8c20dc0, invocation_hint=0xbfcba390) at /build/buildd/glib2.0-2.30.0/./gobject/gclosure.c:774
 signal_emit_unlocked_R (node=0x8ad5250, detail=0, instance=0x8af1680, emission_return=0x0, instance_and_params=0x8c20dc0) at /build/buildd/glib2.0-2.30.0/./gobject/gsignal.c:3272
 g_signal_emit_valist (instance=0x8af1680, signal_id=139, detail=0, var_args=0xbfcba54c "\210}\276\b\a") at /build/buildd/glib2.0-2.30.0/./gobject/gsignal.c:3003