The main UI supports the macOS' toggled light/dark modes, introduced in macOS 10.14 (Mojave).
Changing OS mode should not affect colours set via the app, but simply the main UI (windows, tabs, dialogs, etc.).
New documents created in OS Dark mode will default to using a use a dark Tinderbox built-in colour scheme 'Dark Coral'. The default colour scheme for documents created in OS Light Mode is the built-in scheme 'Modern', from v8.0.0. For documents created before v8, the colour scheme will approximate to
These built-in schemes are listed on, and can applied via, the Colors tab of Document Settings (Edit menu or [Cmd]+8 shortcut).
Therefore when changing mode and desiring app colours suiting the mode, the user must set a new colour scheme of their choice. Two built-in colour schemes have a light/dark pair of schemes: Coral/Dark Coral, and Sunny/Sunny Dark. Changing the document colour scheme is a manual user task and is not automated.
If it is desired to have a 'light' general background to the view pane and $Text area whilst in OS Dark Mode, apply the 'Tinderbox 7' scheme. The KA table and general screen 'chrome' (tabs, etc.) of the app will remain dark but these two key parts of the window will take a light-on-dark colour style.
Likewise, if opening documents that were made in older OS versions or older Tinderbox versions (pre v8) and the colours look wrong, simply apply 'Tinderbox 7': this the document is post v8.0.0, use 'Modern'. Doing this will update the document's colour scheme to reflect the additional colour settings controlled by current colour scheme.
When changing to dark mode or light mode with Tinderbox open, the text colour of the tabs is updated immediately.
See also—notes linking to here: