Rebind org-agenda-clock-goto to `J' in the agenda.

* org-agenda.el (org-agenda-clock-goto): Use `\C-c\C-x\C-j' for
`org-clock-goto' and `J' for `org-agenda-clock-goto'.  If the heading
currently clocked in is not listed in the agenda, display this entry
in another buffer.  If there is no running clock, display a help
message.

* org-clock.el (org-clock-set-current): append the filename after the
heading.

lisp/org-agenda.el

@@ -1666,8 +1666,8 @@ The following commands are available:
 (org-defkey org-agenda-mode-map "O" 'org-agenda-clock-out)
 (org-defkey org-agenda-mode-map "\C-c\C-x\C-x" 'org-agenda-clock-cancel)
 (org-defkey org-agenda-mode-map "X" 'org-agenda-clock-cancel)
-(org-defkey org-agenda-mode-map "\C-c\C-x\C-j" 'org-agenda-clock-goto)
-(org-defkey org-agenda-mode-map "J" 'org-clock-goto)
+(org-defkey org-agenda-mode-map "\C-c\C-x\C-j" 'org-clock-goto)
+(org-defkey org-agenda-mode-map "J" 'org-agenda-clock-goto)
 (org-defkey org-agenda-mode-map "+" 'org-agenda-priority-up)
 (org-defkey org-agenda-mode-map "-" 'org-agenda-priority-down)
 (org-defkey org-agenda-mode-map [(shift up)] 'org-agenda-priority-up)
@@ -7150,7 +7150,12 @@ The cursor may be at a date in the calendar, or in the Org agenda."
 	    (if (eq (overlay-get o 'type) 'org-agenda-clocking)
 		(setq pos (overlay-start o))))
 	  (overlays-in (point-min) (point-max)))
-    (if pos (goto-char pos))))
+    (cond (pos (goto-char pos))
+	  ;; If the currently clocked entry is not in the agenda
+	  ;; buffer, we visit it in another window:
+	  (org-clock-current-task
+	   (org-switch-to-buffer-other-window (org-clock-goto)))
+	  (t (message "No running clock, use `C-c C-x C-j' to jump to the most recent one")))))
 
 (defun org-agenda-diary-entry-in-org-file ()
   "Make a diary entry in the file `org-agenda-diary-file'."

lisp/org-clock.el

@@ -1097,7 +1097,10 @@ the clocking selection, associated with the letter `d'."
   "Task currently clocked in.")
 (defun org-clock-set-current ()
   "Set `org-clock-current-task' to the task currently clocked in."
-  (setq org-clock-current-task (nth 4 (org-heading-components))))
+  (setq org-clock-current-task 
+	(concat (nth 4 (org-heading-components)) 
+		" (" (file-name-nondirectory (buffer-file-name)) ")")))
+
 (defun org-clock-delete-current ()
   "Reset `org-clock-current-task' to nil."
   (setq org-clock-current-task nil))