# Editor Tabs Reference: Singleton tabs

> Why Units, Binder, Output and Rundown only open once.

Glider documentation · The Editor · Web page: https://cgglider.com/docs/editor-tabs/singletons/

Sections of this page: [Catalogue](https://cgglider.com/docs/editor-tabs.md) · [Scene tabs](https://cgglider.com/docs/editor-tabs/scene.md) · [File tabs](https://cgglider.com/docs/editor-tabs/file.md) · [Singleton tabs](https://cgglider.com/docs/editor-tabs/singletons.md)

These tabs edit page-level state rather than one object, so a second copy would be a second view of the same thing — and, for the Binder, a second place for an arming interaction to land. Asking for one that is already open focuses it instead.

That is also why the Poller and Map tabs disappeared: both were folded into Units, and old layouts are migrated to a single Units tab on load.