NOTE: in general documentation the term 'tab' generally refers to per-window tabs and not this tab bar.
Default state: hidden.
From OS 10 Sierra, a document-level tab-bar can be shown, the default is to be hidden. If displayed it shows one tab per open TBX window (N.B. one per window and not one per document). Each tab shows the TBX document's name. It is placed below the toolbar and above the normal (internal) tab bar. The tab bar's visibility is toggled via the Window menu.
This bar allows document windows to be 'docked' to a single tab bar. Discrete document windows within a single document can be docked here.
Any document tab can be dragged off the tab bar to form a discrete document window.
Although document windows from different documents can be docked together, this does not mean in-document tabs can be dragged to different document.
The Window menu has a command to merge all windows which will create one document window with all existing windows/documents as tabs within it.
The tab bar has a '+' symbol at the right side. If clicked, a new un-saved document is created as a new tab on the current windows tab bar.
If a document with docked windows (document tabs) is opened in a pre-Sierra OS, each tab will open as discrete window.
Additional grouping of non-document windows
By using some non-default OS-level settings is is also possible to group additional windows like stand-alone text windows. To do this, the key requirement is:
- in the macOS OS System Settings ▸ Desktop & Dock ▸ Windows (labels as at macOS 26). Set Prefer tabs when opening documents to Always. The OS default for this is Full Screen.
Without this, only document windows can be docked in the toolbar.
Why use this toolbar?
As noted, it is off (hidden) by default. This is because most users likely have no immediate need. however, it is built-in to current Apple frameworks so it is useful for a number of scenarios:
- Some users dislike have a large number of discrete windows for a single app. This tool bar—and the optional OS setting (above)—allows such windows to be collected together.
- On a single/small screen, it may be impractical to display multiple windows at the same time, so grouping this way may make it easier to switch between open Tinderbox windows.
There is no presumption of a 'best' setting here. It is whatever best suits a user's equipment and style of work.
See also—notes linking to here: