Improve display of tabulated list header line labels (bug#44068)

* lisp/emacs-lisp/tabulated-list.el (tabulated-list-init-header):
Ensure sort indicator appears after the label of any selected
sortable column that is wide enough and enable label truncation
when narrowing a column.

* lisp/emacs-lisp/timer-list.el (timer-list-mode): Improve column
alignment.
(timer-list--function-predicate): Correct typo in doc string.

2 files changed, 22 insertions, 16 deletions

diff --git a/lisp/emacs-lisp/tabulated-list.el b/lisp/emacs-lisp/tabulated-list.el
index b13f609f882..30577679f24 100644
--- a/lisp/emacs-lisp/tabulated-list.el
+++ b/lisp/emacs-lisp/tabulated-list.el
@@ -269,42 +269,48 @@ Populated by `tabulated-list-init-header'.")
   ;; FIXME: Should share code with tabulated-list-print-col!
   (let ((x (max tabulated-list-padding 0))
         (button-props `(help-echo "Click to sort by column"
-                        mouse-face header-line-highlight
-                        keymap ,tabulated-list-sort-button-map))
+                                  mouse-face header-line-highlight
+                                  keymap ,tabulated-list-sort-button-map))
+        (len (length tabulated-list-format))
         (cols nil))
     (if display-line-numbers
         (setq x (+ x (tabulated-list-line-number-width))))
     (push (propertize " " 'display `(space :align-to ,x)) cols)
-    (dotimes (n (length tabulated-list-format))
+    (dotimes (n len)
       (let* ((col (aref tabulated-list-format n))
+             (not-last-col (< n (1- len)))
              (label (nth 0 col))
+             (lablen (length label))
+             (pname label)
              (width (nth 1 col))
              (props (nthcdr 3 col))
              (pad-right (or (plist-get props :pad-right) 1))
              (right-align (plist-get props :right-align))
              (next-x (+ x pad-right width)))
+        (when (and (>= lablen 3) (> lablen width) not-last-col)
+          (setq label (truncate-string-to-width label (- lablen 1) nil nil t)))
         (push
          (cond
           ;; An unsortable column
           ((not (nth 2 col))
-           (propertize label 'tabulated-list-column-name label))
+           (propertize label 'tabulated-list-column-name pname))
           ;; The selected sort column
           ((equal (car col) (car tabulated-list-sort-key))
            (apply 'propertize
-                  (concat label
-                          (cond
-                           ((> (+ 2 (length label)) width) "")
-                           ((cdr tabulated-list-sort-key)
+                  (concat label
+                          (cond
+                           ((and (< lablen 3) not-last-col) "")
+                           ((cdr tabulated-list-sort-key)
                             (format " %c"
                                     tabulated-list-gui-sort-indicator-desc))
-                           (t (format " %c"
+                           (t (format " %c"
                                       tabulated-list-gui-sort-indicator-asc))))
-                  'face 'bold
-                  'tabulated-list-column-name label
-                  button-props))
+                  'face 'bold
+                  'tabulated-list-column-name pname
+                  button-props))
           ;; Unselected sortable column.
           (t (apply 'propertize label
-                    'tabulated-list-column-name label
+                    'tabulated-list-column-name pname
                     button-props)))
          cols)
         (when right-align
diff --git a/lisp/emacs-lisp/timer-list.el b/lisp/emacs-lisp/timer-list.el
index 4bda9acebf7..024f0030629 100644
--- a/lisp/emacs-lisp/timer-list.el
+++ b/lisp/emacs-lisp/timer-list.el
@@ -95,8 +95,8 @@
   (setq-local revert-buffer-function #'list-timers)
   (setq tabulated-list-format
         '[("Idle" 6 timer-list--idle-predicate)
-          ("        Next" 12 timer-list--next-predicate)
-          ("      Repeat" 12 timer-list--repeat-predicate)
+          ("Next" 12 timer-list--next-predicate :right-align t :pad-right 1)
+          ("Repeat" 12 timer-list--repeat-predicate :right-align t :pad-right 1)
           ("Function" 10 timer-list--function-predicate)]))
 
 (defun timer-list--idle-predicate (A B)
@@ -121,7 +121,7 @@
     (string< rA rB)))
 
 (defun timer-list--function-predicate (A B)
-  "Predicate to sort Timer-List by the Next column."
+  "Predicate to sort Timer-List by the Function column."
   (let ((fA (aref (cadr A) 3))
         (fB (aref (cadr B) 3)))
     (string< fA fB)))