Recently, I've got my Xubuntu to 16.04 and I found indicators in xfce4-panel have a problem.
As shown in the picture below, volume indicator is missing.
As ugly background color, I don't want to use xfce4-pulseaudio-plugin and xfce4-mixer is unavailable.
Does anyone know how to solve this problem?
You might have indicator-plugin missing from the panel.
Right click on the panel and select
Panel -> Panel Preferences -> Items and click on the + button
Search for Indicator Plugin and add it.
I hope that works.
You can still have xfce4-mixer in Xenial Xerus, though it was removed from official repository for some reasons.
Go to this link of ubuntuupdates.org and download the mixer package's deb file. And then install it with dpkg -i command or gdebi. This worked for me in 16.04 and it doesn't have white background.
Hope this helps.
