Lubuntu desktop installer fails to load desktop window decoratoins on haswell intel desktop with hd 4600 graphics.

To reproduce install the 0417.1 lubuntu desktop amd 64 iso on the desktop. select English at the install menu. Select install lubuntu. at the menu and be connected by wired internet. Then wait for the isntaller to load select something else from the installer.

lxsession:
  Installed: 0.5.2-0ubuntu1
  Candidate: 0.5.2-0ubuntu1
  Version table:
 *** 0.5.2-0ubuntu1 0
        500 http://archive.ubuntu.com/ubuntu/ vivid/universe amd64 Packages
        100 /var/lib/dpkg/status
lxsession:
  Installed: 0.5.2-0ubuntu1
  Candidate: 0.5.2-0ubuntu1
  Version table:
 *** 0.5.2-0ubuntu1 0
        500 http://archive.ubuntu.com/ubuntu/ vivid/universe amd64 Packages
        100 /var/lib/dpkg/status

I expected the desktop installer to have window decoartion and window managment so if for example I click on the release notes and opened a web browswer I could click the close button and close the window.

Instead there were not window decorations so new users wouldn't have an obvious way to close the release notes for example. The installer still seems to be working however when selecting somethings else.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: lxsession 0.5.2-0ubuntu1
ProcVersionSignature: Ubuntu 3.19.0-14.14-generic 3.19.3
Uname: Linux 3.19.0-14-generic x86_64
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
CasperVersion: 1.359
Date: Sat Apr 18 17:38:34 2015
LiveMediaBuild: Lubuntu 15.04 "Vivid Vervet" - Beta amd64 (20150417.1)
ProcEnviron:
 TERM=linux
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: lxsession
UpgradeStatus: No upgrade log present (probably fresh install)