How to check if Cancel button was clicked on ManagedUI standard UI dialogs?

[Fiinleyyy]

Hi,

I've seen similiar questions before but none of them could quite help me. I would like to catch if the user pressed the cancel button during install or afterinstall.

During AfterInstall a script creates new files which are not rollbacked when the user is pressing cancel (obviously since MSI won't be aware of them) - but how can I detect user cancellation?

I heard @oleg-shilo say to use the CustomUI template and use the onClick Event. But I am using ManagedUI with default dialogs that's why I am unsure how and if I can access the onClick event.

I'd appreciate some help (:

Greetings
Finley