To answer Nicolas’s question, it was the wrong switch used.
Instead of -AllowDefer, if you use -AllowDeferCloseApps, the installation Windows will only show if there is a CloseApps:
Show-InstallationWelcome -CloseApps ‘chrome=Google Chrome’ -AllowDeferCloseApps
I added a new switch to Show-InstallationWelcome to show the closing app Windows even in silent mode. This way, you don’t see every other window the installation pops up, but if apps should be closed, they won’t close drastictly.
Show-InstallationWelcome -CloseApps ‘chrome=Google Chrome’ -AllowDeferCloseApps -DeferTimes 3 -ShowClosingAppsInSilent
You can get my fork here:
https://github.com/RichardLafontaine/PSAppDeployToolkit/tree/master/Toolkit/AppDeployToolkit
It’s a fork of the yet to be released version 3.6.9 though.