Version: 28.0.50
Tags: patch

The same way as quit-window deletes the frame
when quitting the last window on the frame with e.g.

  C-x 5 d RET q

this patch implements the same behavior for tabs:

  C-x t d RET q

closes the tab.

This is for master since it will take time to tweak.
For example, it works fine everywhere except Gnus
that doesn't call quit-window when exiting a summary buffer
typing `q' (gnus-summary-exit) in a summary buffer
that was automatically displayed in a new tab,
so needed to customize Gnus by

  (add-hook 'gnus-summary-exit-hook 'quit-window)