gala crashed with SIGSEGV in gala_workspace_thumb_update_windows()

[Nikki1993]

I have no idea why this has happened. I was browsing the web with Firefox when suddenly entire system froze, blinked and went back to it's normal state with bug report pop-up.

ProblemType: Crash
DistroRelease: elementary OS 0.2
Package: gala 0.1-0~r329+pkg18~precise1 [origin: LP-PPA-elementary-os-daily]
Uname: Linux 3.9.2-030902-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.2+elementary3~precise1
Architecture: amd64
CrashDB: gala
Date: Sun May 12 16:13:33 2013
ExecutablePath: /usr/bin/gala
GsettingsChanges:

InstallationMedia: elementary OS 0.2 "Luna" - Beta 2 amd64 (20130506)
MarkForUpload: True
ProcCmdline: gala
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SegvAnalysis:
 Segfault happened at: 0x437a7e: mov (%rax),%rax
 PC (0x00437a7e) ok
 source "(%rax)" (0xffffffffd4001300) not located in a known VMA region (needed readable region)!
 destination "%rax" ok
SegvReason: reading unknown VMA
Signal: 11
SourcePackage: gala
StacktraceTop:
 ?? ()
 ?? ()
 ?? ()
 ?? ()
 ffi_call_unix64 () from /usr/lib/x86_64-linux-gnu/libffi.so.6
Title: gala crashed with SIGSEGV in ffi_call_unix64()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo

[RabbitBot (rabbitbot-a)]

StacktraceTop:
 gala_workspace_thumb_update_windows (self=0x18b8780) at /build/buildd/gala-0.1/src/Widgets/WorkspaceThumb.vala:359
 gala_workspace_thumb_handle_window_removed (self=0x18b8780, window=0x1b46550) at /build/buildd/gala-0.1/src/Widgets/WorkspaceThumb.vala:482
 gala_workspace_thumb_window_left_monitor (self=0x18b8780, num=0, window=0x1b46550) at /build/buildd/gala-0.1/src/Widgets/WorkspaceThumb.vala:342
 _gala_workspace_thumb_window_left_monitor_meta_screen_window_left_monitor (_sender=0x16211c0, object=0, p0=0x1b46550, self=0x18b8780) at /build/buildd/gala-0.1/src/Widgets/WorkspaceThumb.vala:263
 ffi_call_unix64 () at ../src/x86/unix64.S:75