Wingpanel doesn't revert to transparent mode

[Izzy Maxino]

I notice that maximizing a window will change the wingpanel to an opaque black. Sometimes when I close or unmaximize/minimize a window, the wingpanel does not revert to its transparent mode. When it is like this, most of the time, the wingpanel stops responding, e.g. super+spacebar does not work, clicking on "Applications" does not work, or clicking on any of the wingpanel icons does not work. At other times, the wingpanel still responds even when it did not revert to its transparent mode.

ProblemType: Bug
DistroRelease: elementary 0.4
Package: elementary-desktop 1.412+467~daily~ubuntu0.4.1 [origin: LP-PPA-elementary-os-daily]
ProcVersionSignature: Ubuntu 4.4.0-24.43-generic 4.4.10
Uname: Linux 4.4.0-24-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CrashDB: elementary_meta
CurrentDesktop: Pantheon
Date: Mon Jun 20 12:21:34 2016
InstallationDate: Installed on 2016-06-19 (0 days ago)
InstallationMedia: elementary OS 0.4 "Loki" - Daily amd64 (20160613)
ProcEnviron:
 LANGUAGE=en_US
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: elementary-meta
SuspiciousXErrors:

ThirdParty: True
UpgradeStatus: No upgrade log present (probably fresh install)

[Ivo (ivolopesribeiro15)]

same here

[Zisu Andrei (matzipan)]

For the freezing issue, there's a report in bug #1604612 .

I will repurpose this issue for the issue where wingpanel doesn't change it background.