Just experimenting with the "abort" command. I have it in a function (not a callback one) and it does not work:
1)With "BCGgradient" the blue background screen will just stay and you have to kill the process. Without it will exit, but the installer.exe will still be locked by the OS (cannot delete it) afterwards.
2)It also never displayed any "UserMessage".
(But I use "AutoClose on", so that might be a reason if it is shown in the installer window...)