Hi,

Clicking on the find-abbreviate ellipsis in a grep-mode buffer
while focus is on another emacs window invokes the
grep-find-toggle-abbreviation on the buffer in the focused window
instead of in the clicked window.

The common manifestation of this problem would be a user error because the
abbreviated-command property can not be found. More interesting results
can be achieved if the focused window contains another grep-mode buffer
in which case the ellipsis will be expanded in the focused window
instead of the clicked.

Attaching a patch the invokes mouse-select-window before toggling the
abbreviation.

Best regards,
David Landell