Option to change Application Switcher color/opacity is broken

Steps to Re-create:

# Open compizconfig-settings-manager
# Enable Application switcher plugin
# In the plugin settings go to the general tab
# In the Background section check 'Set background color'
# and below that specify the desired background color and opacity

Expected: Should change background color and opacity of the application switcher

Actual: There's absolutely no change, even after restarting compiz

IMO this is a big issue, because the defaults for the application switcher are horrible - it has a highly transparent background by default making window titles hard to read, and because this setting is broken it's impossible to change it

This also happens with the equivalent setting in the Static Application switcher plugin as well

IMO in addition to fixing this, the default should really be changed well to have a more opaque background for the switchers... this is an accessibility issue. Take a look at the attached screenshot, this looks horrible and the titles are hard to read

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: compiz 1:0.9.13.1+18.04.20180302-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-23.25-generic 4.15.18
Uname: Linux 4.15.0-23-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: MATE
Date: Mon Jul 2 07:36:48 2018
DistUpgraded: Fresh install
DistroCodename: bionic
DistroVariant: ubuntu
GraphicsCard:
 Intel Corporation HD Graphics 620 [8086:5916] (rev 02) (prog-if 00 [VGA controller])
   Subsystem: Dell HD Graphics 620 [1028:075b]
InstallationDate: Installed on 2018-07-01 (0 days ago)
InstallationMedia: Ubuntu-MATE 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 003: ID 0bda:568b Realtek Semiconductor Corp.
 Bus 001 Device 002: ID 8087:0a2b Intel Corp.
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Dell Inc. XPS 13 9360
PackageArchitecture: all
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-23-generic root=UUID=1c4a86ff-5873-4915-ad29-4ddb2860d2a4 ro quiet splash resume=UUID=090c8a9c-8385-4ef9-9b9f-351429c9bac6 vt.handoff=1
SourcePackage: compiz
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/21/2018
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 2.7.1
dmi.board.name: 0JGD96
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr2.7.1:bd05/21/2018:svnDellInc.:pnXPS139360:pvr:rvnDellInc.:rn0JGD96:rvrA00:cvnDellInc.:ct9:cvr:
dmi.product.family: XPS
dmi.product.name: XPS 13 9360
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.13.1+18.04.20180302-0ubuntu1
version.libdrm2: libdrm2 2.4.91-2
version.libgl1-mesa-dri: libgl1-mesa-dri 18.0.0~rc5-1ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx 18.0.0~rc5-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.6-1ubuntu4
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:18.0.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20171229-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2