With HyperCard 2.0, you can switch to another application under MultiFinder while a script is running, and the script will continue to execute. The sorting and compacting operations also work while HyperCard is in the background.
HyperCard notifies the user whenever the user’s intervention is required while it runs in the background (for example, a script wants to display a dialog box). When this occurs, HyperCard beeps, puts a diamond next to its name in the Apple menu, and flashes its small icon in the menu bar.