Busy yesterday, and delving deeper (using v7.1.0):
The New Tab command is seen on the Tab sub-menu of the View menu:
There is no shortcut defined for this option.Note the menu string is 'New Tab', not 'Open New Tab' or 'Create New Tab'. I not this in case it is necessary to correctly find/map this item.
A variant of "Show Original In New Tab"is also seen on the View pane's context menu, when an alias is selected.
The Font sub-menu of the format menu includes the Show Font option, for which the system-level Cmd+T shortcut is mapped:
- Tinderbox binds Cmd+T to the system Fonts dialog
- There is a menu to open a new tab: View menu -> Tabs -> New Tab. No shortcut is defined.