Desktop locks up after right clicking item in launch menu

[Chad Berchek]

1. Open a window (any window should do...PCManFM is convenient)
2. Left click the launcher Menu icon on the task bar
3. Hover over a group to expand the sub-menu
4. Right-click any item in the sub-menu
5. Left click again on the Menu icon on the task bar again
6. The desktop becomes unresponsive to clicks

Notes:
* It may take more than one attempt but usually it happens on the first or second try.
* Step #1 may be unnecessary but it seems to be easier to observe it more quickly if you already have at least one window open
* Quick launch icons on the task bar may still respond to clicks even after everything else is locked up; if you continue clicking around on different things eventually they will stop working as well
* Interestingly, items on the task bar still highlight when the mouse moves over them but they appear unresponsive to clicks, as do application windows and window decorations (e.g., close button)

Lubuntu 14.04.2 x86_64

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: lubuntu-desktop 0.55
ProcVersionSignature: Ubuntu 3.16.0-41.55~14.04.1-generic 3.16.7-ckt11
Uname: Linux 3.16.0-41-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.11
Architecture: amd64
Date: Fri Jun 19 22:07:32 2015
InstallationDate: Installed on 2015-06-17 (3 days ago)
InstallationMedia: Lubuntu 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1)
ProcEnviron:
 TERM=linux
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: lubuntu-meta
UpgradeStatus: No upgrade log present (probably fresh install)

[Chris Guiver (guiverc)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. We are sorry that we do not always have the capacity to look at all reported bugs in a timely manner. There have been many changes in Ubuntu since that time you reported the bug and your problem may have been fixed with some of the updates. It would help us a lot if you could test it on a currently supported Ubuntu version. When you test it and it is still an issue, kindly upload the updated logs by running only once:
apport-collect <bug #>

and any other logs that are relevant for this particular issue.

[Launchpad Janitor (janitor)]

[Expired for lubuntu-meta (Ubuntu) because there has been no activity for 60 days.]