XFCE4 / debian buster - botão alternar usuário veio sem funcionalidade [RESOLVIDO]

User switching action button is greyed out

The Switch User action button assumes that the gdmflexiserver executable (provided by GDM) exists. Thus, if GDM is not being used then the button will be greyed out. See the upstream bug report.

A possible workaround is to create an executable script called gdmflexiserver in /usr/bin or /usr/local/bin which calls the greeter switch command provided by the display manager which is being used.

For LXDM - LXDM#Simultaneous users and switching users.
For LightDM - LightDM#User switching.

Hello and welcome.

Switch user functionality is dependent on the Display Manager that you are using and whether it supports user switching. In addition, the Xfce Actions button panel plugin assumes that gdmflexiserver is installed (GDM) and uses that to switch users.

Since it's greyed out, it means that you are not using GDM.

If you are using Lightdm, then with root privileges, create the file /usr/local/bin/gdmflexiserver with the following content:

#!/bin/sh

dm-tool switch-to-greeter
...and make the file executable.

If you are using another display manager (and assuming that it supports user switching), you will need to do something similar but replace the command in the gdmflexiserver code above to use that specific display manager's user switching command/functionality.