xfce4-mixer-4.6.1-alt2 The mixer applet is running, but there is an empty place instead of an icon on the panel. Perhaps something is missing, but I expect "apt-get install" to install everything necessary for a program. Here is a list of my Xfce-related and icon-related packages: $ rpm -qa '*xf*' xfce4-dict-plugin-0.3.0-alt1 xfce4-smartbookmark-plugin-0.4.2-alt1 xfce4-genmon-plugin-3.2-alt1 xfce4-netload-plugin-0.4.0-alt1 xfce4-mailwatch-plugin-1.0.2-alt0svn3751 xfce4-fsguard-plugin-0.4.2-alt1 libXxf86misc-1.0.1-alt2 xfce-settings-desktop-network-0.6-alt1 xfce4-cddrive-plugin-0.0.1-alt1 xfce4-gsynaptics-plugin-1.0.0-alt1.1 xfce4-taskmanager-0.4.1-alt1 xfprint-4.6.1-alt2 gnome-vfs-obexftp-0.4-alt1 xfce4-notes-plugin-1.6.3-alt1 xfce4-panel-4.6.1-alt0.M50.2 xfsprogs-2.10.1-alt1 xfce4-icon-theme-4.4.3-alt1 xfce4-systemload-plugin-0.4.2-alt1.1 xfce-mousepad-0.2.14-alt1 xfce4-timer-plugin-0.6.1-alt1 xfce4-session-engines-4.6.1-alt1 libxfs-2.10.1-alt1 xfce4-smartpm-plugin-0.4.0-alt1 xfce4-diskperf-plugin-2.2.0-alt1 libxfcegui4-4.6.1-alt0.M50.2 xfce4-session-4.6.1-alt1 xfce4-xkb-plugin-0.5.3.3-alt1 fonts-ttf-latex-xft-0.1-alt4 libobexftp-0.22-alt2 xfsinfo-1.0.2-alt2 xf86dga-1.0.2-alt1 xfce4-places-plugin-1.0.0-alt1 xfcalendar-4.6.1-alt1 xfce4-xfmpc-0.0.7-alt1 xfce4-wmdock-plugin-0.2.0-alt1 xfce4-eyes-plugin-4.4.0-alt1 xfce4-mpc-plugin-0.3.3-alt1 xfconf-utils-4.6.1-alt2 xfce4-clipman-plugin-0.8.1-alt1 xfce4-datetime-plugin-0.6.1-alt1 xfce4-power-manager-0.8.1-alt1 libgtk-engines-xfce4-2.4.0-alt0.2 xfce4-cpugraph-plugin-0.4.0-alt1 xfdesktop-4.6.1-alt2 xfce-settings-desktop-0.6-alt1 xfce-mcs-manager-4.4.3-alt1 xfd-1.0.2-alt1 libXxf86vm-1.0.2-alt2 xfce4-minimal-4.6-alt1 obexftp-0.22-alt2 xfce4-appfinder-4.6.1-alt2 libxfconf-4.6.1-alt2 xfce-utils-4.6.1-alt4 xorg-x11-xfs-1.0.6-alt1 libxfce4util-4.6.1-alt1 xfce4-weather-plugin-0.6.2-alt1 xfce-mcs-plugins-4.4.3-alt1 libxfce4mcs-4.4.3-alt1 xfce4-radio-plugin-0.4.0-alt1 xfce4-cpufreq-plugin-0.2-alt0svn3751 xfce4-mixer-4.6.1-alt2 xfce4-battery-plugin-0.5.1-alt1 xfce4-xmms-plugin-0.5.1-alt1 xfce4-xfapplet-plugin-0.1.0-alt1 xfce4-quicklauncher-plugin-1.9.4-alt1 xfontsel-1.0.2-alt2 xfce4-mount-plugin-0.5.5-alt1 xfce4-modemlights-plugin-0.1.3.99-alt1 fuse-obexfs-0.11-alt0.rc3 xfce4-time-out-plugin-0.1.1-alt1 xfce4-xfmedia-0.9.2-alt2.1 libxforms-1.0.90-alt1.1 xfce4-screenshooter-plugin-1.4.0-alt1 python-module-obexftp-0.22-alt2 libxfsm-4.6.1-alt1 libxfce4util-devel-4.6.1-alt1 xfce4-sensors-plugin-0.10.99.6-alt1 libXxf86dga-1.0.2-alt2 xfig-3.2.5_alpha5-alt8 xfce4-xfbib-0.0.2-alt1 libxfce4menu-4.6.1-alt1 libxfce4mcs-devel-4.4.3-alt1 xfce4-cellmodem-plugin-0.0.5-alt1.1 xfce4-terminal-0.2.8.3-alt1 xfwm4-4.6.1-alt2 $ rpm -qa '*icon*' icons-BlueSphere-0.3.0-alt5 icon-theme-mist-2.26.1-alt1 quodlibet-plugin-trayicon-0-alt2.1 qmmp-statusicon-0.2-alt0.1.svn376 alterator-icons-default-0.2-alt1 xfce4-icon-theme-4.4.3-alt1 icon-theme-crux-2.26.1-alt1 gnome-icon-theme-2.26.0-alt1 tango-icon-theme-extras-0.1.0-alt1 fvwm-icons-2.5.16-alt3 icon-theme-gnome-colors-wine-3.6-alt1 ruby-module-iconv-1.8.7-alt7 icon-theme-gnome-colors-noble-3.6-alt1 tango-icon-theme-0.8.90-alt1 gnome-icon-themes-crystal-1.0-alt1 gnome-icon-themes-old-1.0-alt2 icon-themes-accessibility-2.26.1-alt1 menu-icons-default-0.1-alt2 muine-plugin-trayicon-0.8.10-alt2 icon-theme-gnome-colors-wise-3.6-alt1 icon-naming-utils-0.8.90-alt1 iconv-2.9-alt3 icon-theme-gnome-colors-brave-3.6-alt1 gnome-icon-themes-extra-1.0-alt2 icon-theme-hicolor-0.5-alt1 gnome-icon-themes-industrial-0.2.36-alt1 $
The upgrade from icon-theme-hicolor-0.5-alt1 to icon-theme-hicolor-0.10-alt2 helped. I think that xfce4-mixer should require a fresh icon-theme-hicolor, otherwise it's not quite useable (or perhaps the formal requirement should be very fine-grained: the name of the icon, and the package with icons should list all its icons as "provides").
BTW, it's a well-known issue in the world: http://forum.xfce.org/index.php?topic=4701.0 , http://forum.xfce.org/index.php?topic=5204.0 , etc.: http://www.google.com/search?ie=UTF-8&oe=UTF-8&q=%22no+icon%22+xfce+mixer ...
Branch 5.0 is not supported.