With Application Wizard you can customize the behavior of applications.
You can for instance prevent some applications from hiding in single application mode or when you choose Hide Others.
Open the Application Wizard pane in System Preferences and click Applications.
Important: Custom behavior of applications is limited to Application Wizard. If you want applications to open in a custom way, you must launch them with Application Wizard. Similarly, if you want to keep applications visible when you hide the other applications, you must use Application Wizard’s Hide Others command.