README.MD

Batch QZ Tray Session Stealer

Custom session stealer for Windows fast user switching

For a pure PowerShell solution, see here instead: https://gist.github.com/tresf/4e19e15ad38354af6732ee701c990102

Problem

• QZ Tray is a singleton application, so only one instance can run at a time.
• Windows fast-user switching feature leaves applications running when a new user signs onto a shared workstation
• QZ Tray can "steal" the instance, however this is retroactive and places a burden on the user

Solution

• A solution is to detect that a user switch has occured and start QZ Tray on the new desktop automatically

Limitations

• This should ONLY be run on shared workstations with one user at a time. Terminal Server environments should instead leverage a dedicated print-server solution.

Steps

1. Copy start_if_active.bat to C:\Program Files\QZ Tray\
2. Import Steal QZ Tray At Login.xml to Task Scheduler
3. Test fast-user switching

start_if_active.bat

@ECHO OFF
REM Author: tres@qz.io

FOR /F "skip=1" %%g IN ('WMIC COMPUTERSYSTEM GET USERNAME') DO (IF NOT DEFINED LOGGED_USER SET LOGGED_USER=%%g)

REM Note: "": =%"" will Remove spaces from WMIC output when comparing
IF /I "%LOGGED_USER: =%" == "%USERDOMAIN%\%USERNAME%" (
    "%~dp0qz-tray.exe" --steal
    SET MSG=[start_if_active.bat] %DATE% %TIME% SUCCESS: "%USERDOMAIN%\%USERNAME%" is active, starting "%~dp0qz-tray.exe"
    COLOR 0A
) ELSE (
    SET MSG=[start_if_active.bat] %DATE% %TIME% SKIPPED: "%USERDOMAIN%\%USERNAME%" is NOT active, skipping "%~dp0qz-tray.exe"
    COLOR 0C
)

ECHO %MSG%
ECHO %MSG% >> %APPDATA%\qz\task-scheduler.log

REM PAUSE

Steal QZ Tray At Login.xml

<?xml version="1.0" encoding="UTF-16"?>
<Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">
  <RegistrationInfo>
    <Date>2022-12-13T12:29:01.6615572</Date>
    <Author>tres@qz.io</Author>
    <URI>\Steal QZ Tray at Login</URI>
  </RegistrationInfo>
  <Triggers>
    <EventTrigger>
      <Enabled>true</Enabled>
      <Subscription>&lt;QueryList&gt;&lt;Query Id="0" Path="Security"&gt;&lt;Select Path="Security"&gt;*[EventData[ (Data[@Name='LogonType']=2) and (Data[@Name='ElevatedToken']='%%1843')]] and *[System[(EventID=4624)]]&lt;/Select&gt;&lt;/Query&gt;&lt;/QueryList&gt;</Subscription>
    </EventTrigger>
  </Triggers>
  <Principals>
    <Principal id="Author">
      <GroupId>S-1-5-32-545</GroupId>
      <RunLevel>LeastPrivilege</RunLevel>
    </Principal>
  </Principals>
  <Settings>
    <MultipleInstancesPolicy>StopExisting</MultipleInstancesPolicy>
    <DisallowStartIfOnBatteries>false</DisallowStartIfOnBatteries>
    <StopIfGoingOnBatteries>false</StopIfGoingOnBatteries>
    <AllowHardTerminate>true</AllowHardTerminate>
    <StartWhenAvailable>false</StartWhenAvailable>
    <RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable>
    <IdleSettings>
      <StopOnIdleEnd>false</StopOnIdleEnd>
      <RestartOnIdle>false</RestartOnIdle>
    </IdleSettings>
    <AllowStartOnDemand>true</AllowStartOnDemand>
    <Enabled>true</Enabled>
    <Hidden>false</Hidden>
    <RunOnlyIfIdle>false</RunOnlyIfIdle>
    <WakeToRun>false</WakeToRun>
    <ExecutionTimeLimit>PT0S</ExecutionTimeLimit>
    <Priority>7</Priority>
  </Settings>
  <Actions Context="Author">
    <Exec>
      <Command>cmd.exe</Command>
      <Arguments>/c start_if_active.bat</Arguments>
      <WorkingDirectory>%PROGRAMFILES%\QZ Tray\</WorkingDirectory>
    </Exec>
  </Actions>
</Task>