org-clock-frame-title-format

org-clock-frame-title-format is a variable defined in `org-clock.el'.
Its value is

(t org-mode-line-string)

Documentation:
The value for `frame-title-format' when clocking in.

When `org-clock-clocked-in-display' is set to 'frame-title
or 'both, clocking in will replace `frame-title-format' with
this value. Clocking out will restore `frame-title-format'.

`org-frame-title-string' is a format string using the same
specifications than `frame-title-format', which see.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.1 of Emacs.