Actually this specific issue effects the default Ubuntu session as well. I did a fresh install of 18.04.2, installed updates, rebooted, and checked it out to be sure. Then I filed bug #1817625 so one or the other needs to be marked a duplicate (and changed back to "new" rather than "invalid"). I just wanted to collect all the logs so you could see I'm not pulling your leg about the default Ubuntu session being effected.
I had not realized that the default Ubuntu session had a UI for over- amplification whereas flashback session does not. Since it can be set via dconf I'm unlikely to file a new bug report just for that. I should however check to be sure flashback doesn't "break" things in a default session. I just got lazy yesterday and filed this bug report from my workhorse PC rather than using my friends new HTPC. I'm going to rinse-n-repeat the steps to reproduce this in that unmolested install of Bionic. It seems that either a reboot or logout is needed after selecting over-amplification = on. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to gnome-control-center in Ubuntu. https://bugs.launchpad.net/bugs/1817485 Title: Bionic "amplified" sound controls do not sync with volume slider Status in gnome-control-center package in Ubuntu: Invalid Bug description: I'm just setting up my first Bionic HTPC and I notice that if you select allow-amplified-volume in dconf that change only applies to the volume slider, not to the sound control UI. This results in the volume hot-keys not controlling sound above 100%. So if you're watching video content in full screen you must ESC, then use the volume slider, and then go back to full screen. It makes for an unwieldy process so using a different DE becomes a temptation. You can see what I'm talking about in the attached screenshot. ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: gnome-control-center 1:3.28.2-0ubuntu0.18.04.2 ProcVersionSignature: Ubuntu 4.15.0-45.48-generic 4.15.18 Uname: Linux 4.15.0-45-generic x86_64 ApportVersion: 2.20.9-0ubuntu7.5 Architecture: amd64 CurrentDesktop: GNOME-Flashback:GNOME Date: Sun Feb 24 14:10:03 2019 InstallationDate: Installed on 2018-01-28 (391 days ago) InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719) SourcePackage: gnome-control-center UpgradeStatus: Upgraded to bionic on 2018-08-15 (193 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-control-center/+bug/1817485/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp

