The Sprawling Workspaces
macOS features a powerful virtual desktop manager called Mission Control (formerly Spaces). This allows you to create multiple, separate desktop environments to organize your windows. However, macOS sometimes attempts to be overly helpful by automatically creating new desktops without your permission. This usually happens when you take a specific application (like Safari or a video player) and make it full-screen by clicking the green button in the top-left corner of its window. macOS instantly creates a brand-new, temporary desktop space just for that app, which can disrupt your carefully organized workflow and confuse your navigation.
Containing Full-Screen Apps
To maintain a predictable environment and stop macOS from automatically creating new desktops (Spaces) when you maximize an application, you must alter how the operating system handles full-screen behavior.
Unfortunately, Apple does not provide a direct toggle to stop full-screen apps from creating their own space; it is a fundamental design of the modern macOS full-screen API. However, you can prevent the behavior by holding the Option key on your keyboard before you click the green maximize button. When you hold Option, the green button changes from a “Full Screen” icon (two arrows) to a “Zoom” icon (a plus sign). Clicking it will now expand the window to fill the available space on your current desktop, rather than throwing it into a brand-new virtual space. To stop applications from opening in previously used spaces, go to System Settings > Desktop & Dock, scroll down to Mission Control, and uncheck “Group windows by application.”