Arrange strip
Compact Arrange popup
When an app has only one or two windows on the current desktop, the Arrange strip opens as a small popup with just those windows. Each picture keeps the shape of its monitor.
A button such as "+2 on Desktop 5" shows the windows of the app on other desktops. You can also press → on the keyboard. These windows stay faded until you select one. Enter or a click on one opens it, and Windows switches to its desktop.
With three or more windows on this desktop, the full strip opens as before.