XFCE - Lightweight desktop environment for UNIX-like OS

XFCE : all icons are gone, Gtk-WARNING **: Error loading theme icon ... Unrecognized image format

Situation :

... and suddendly : no more icons anywhere (desktop, taskbar, notification pop-ups, even on the login window !!!) Just empty spaces, and _sometimes_ a "broken image" icon.

Details :

The full error messages can be found :

See this for details (this was on the browser tab right after the one providing the solution below, so did not read it yet

Solution :

  1. updatedb && locate gdk-pixbuf-query-loaders
    /usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/gdk-pixbuf-query-loaders
  2. /usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/gdk-pixbuf-query-loaders > /usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders.cache
And it was fixed right away, no need to log out or reboot

Solutions that dit not fix it

For future reference or extra hints, here are some additional sources that may help, even though they didn't work for me :
https://petermolnar.net/solution-for-gtk-warning-error-loading-theme-icon/
As root :
	for i in /usr/share/icons/*; do gtk-update-icon-cache $i; done
==========================================&<=========================================================
https://askubuntu.com/questions/822770/desktop-flickers-icons-white
	apt install --reinstall xfdesktop4
==========================================&<=========================================================
https://forums.fedoraforum.org/showthread.php?280639-Icons-and-images-disappeared-can-t-login-in-gnome-shell
As root :
	update-mime-database /usr/share/mime
	chmod 664 /usr/share/applications/mimeinfo.cache
	reboot

XFCE : how to switch users ?

Situation :

I'd like to switch users while running an XFCE session (without closing the current session), but the Switch User option of the "Action Buttons" desktop applet is disabled.

Solution :

Quick and dirty solution I wouldn't recommend (source) :

apt-get install xfswitch-plugin

This may do the trick, but this will install ~100MB of Gnome stuff and libs, and I don't want that. Using the --no-install-recommends flag turns this down to ~40MB, but it's still too much.

A more acceptable solution :

  1. Lock the current session
  2. On the lock screen, click
  3. Enter the login credentials and voilà !

At the lock screen step, this may fail saying : Could not execute "gdmflexiserver": No such file or directory.
In such case, as (source) :

newFile='/usr/local/bin/gdmflexiserver'; cat << EOF > $newFile
#!/bin/sh
# replacement for missing gdmflexiserver
dm-tool switch-to-greeter
EOF
chmod 775 $newFile

How to launch a program upon graphical session opening ?

Gnome
(for the current user only) : [Start menu] | System | Preferences | Startup applications
XFCE
  1. [Start menu] | Settings | Settings Manager | Session and Startup | Application Autostart tab
  2. Click
  3. Then enter values :
    Field Value
    Name dualScreen
    Description Auto-configure dual-screen
    Command /usr/bin/xrandr --output DVI-1 --left-of DVI-0

    The binary must be specified with its absolute path.

The "freedesktop.org" method :

  1. Create a /home/bob/.config/autostart/myStartupApp.desktop
  2. Edit it such as (Specification, Syntax) :
    [Desktop Entry]
    Type=Application
    Exec=/path/to/binary args
    Hidden=false
    X-GNOME-Autostart-enabled=true
    Name[fr_FR]=myStartupApp
    Name=myStartupApp
    Comment[fr_FR]=
    Comment=
  3. You're done ! This new entry should also be visible through the Gnome startup apps configuration menu.

These settings apply to only. To apply them system-wide, create the myStartupApp.desktop file in /etc/xdg/autostart/ instead of /home/bob/.config/autostart/.
If all users are happy with these settings and isn't, he can override them with his own myStartupApp.desktop file. He may also disable the launch of myStartupApp with Hidden=true in his config file.

This method is being standardized and should work with Gnome, KDE and others.

The colors of XFCE Terminal are too dark

Instead of a bright yellow (for commit IDs in git log output), a dark brown is used. The blue too is too dark, especially when displaying text over a black background. To tune these colors :
  1. Within XFCE Terminal window : Edit | Preferences | Colors
  2. Tango looks ok to me
  3. This loads a color palette, then you can fine-tune colors individually