I am using a MacBook for work now. Got a stuck installer, trying to restart the computer.
Messages (not exact quotes).
The system: cannot restart, please exit installer [Cancel], [Try again].
Installer: Installer is busy, cannot close window. [OK]
Check and mate.
Fortunately, the restart attempt must have killed some processes that were interfering with the installer, so it went on. Otherwise, I am not sure what I could do: this thing doesn’t even have a power button!
PS. Upon shutdown/restart Windows kills stubborn processes after 30 seconds if they don’t cooperate.