add new arrow glyphs ↔↕ with good font support

README.org

@@ -991,7 +991,7 @@ In this example, =C-<insert>= was chosen. You can use whatever keys combination
 
 - =make-box.el=: box around part of a buffer
 
-- =Vim DrawIt ascii diagrams=: in Vin, in ASCII
+- =vim drawit ascii diagrams=: in Vin, in ASCII
 
 * Author, contributors
 - Thierry Banel, author

uniline.el

@@ -1,4 +1,4 @@
-;;; uniline.el --- Draw text diagrams using UNICODE characters -*- coding:utf-8; lexical-binding: t; -*-
+;;; uniline.el --- Add UNICODE based diagrams to text files -*- coding:utf-8; lexical-binding: t; -*-
 
 ;; Copyright (C) 2024  Thierry Banel
 
@@ -755,10 +755,10 @@ without the fall-back characters.")
       (a   ?↑ ?→ ?↓ ?←)      ;; *wards arrow
       (a   ?▵ ?▹ ?▿ ?◃)      ;; white *-pointing small triangle"
       (a   ?▴ ?▸ ?▾ ?◂)      ;; black *-pointing small triangle
-
+      (a   ?↕ ?↔ ?↕ ?↔)      ;; up down arrow, left right arrow
+
       ;; Those commented-out arrows are monospaces and supported
       ;; by the 6 fonts.  But they do not have 4 directions.
-      ;;(a   ?↕ ?↔ ?↕ ?↔)      ;; up-dw-lf-ri arrow
       ;;(a   ?‹ ?› ?› ?‹)      ;; single *-pointing angle quotation mark
 
       ;; squares
@@ -2325,7 +2325,7 @@ When FORCE is not nil, overwrite whatever is in the buffer."
     "Text dir─╴%s(uniline--text-direction-str)╶"
   "\
 ╭^─^─^Insert glyph^─────╮╭^Rotate arrow^╮╭^Text dir────^╮╭^─Contour─^╮╭^─^─^─^─^─^─^─^────────────╮
-│_a_,_A_rrow   ▷ ▶ → ▹ ▸││_S-<left>_  ← ││_C-<left>_  ← ││_c_ contour││_-_ _+_ _=_ _#_ self-insert│
+│_a_,_A_rrow ▷ ▶ → ▹ ▸ ↔││_S-<left>_  ← ││_C-<left>_  ← ││_c_ contour││_-_ _+_ _=_ _#_ self-insert│
 │_s_,_S_quare  □ ■ ◇ ◆ ◊││_S-<right>_ → ││_C-<right>_ → ││_C_ ovwrt  ││_f_ ^^^^^^      choose font│
 │_o_,_O_-shape · ● ◦ Ø ø││_S-<up>_    ↑ ││_C-<up>_    ↑ │╭^─Fill────^╮│_TAB_   ^^^^^^  short hint │
 │_x_,_X_-cross ╳ ÷ × ± ¤││_S-<down>_  ↓ ││_C-<down>_  ↓ ││_i_ fill   ││_q_ _RET_ ^^^^  exit       │
@@ -2672,7 +2672,7 @@ And backup previous settings."
 │ enter a sub-mode to draw a single character glyph,
 │ and change its orientation.
 ├─Intersection glyphs────────╴\\<uniline-hydra-arrows/keymap>
-│ \\[uniline-hydra-arrows/uniline-insert-fw-arrow]	arrows   ▷ ▶ → ▹ ▸
+│ \\[uniline-hydra-arrows/uniline-insert-fw-arrow]	arrows ▷ ▶ → ▹ ▸ ↔
 │ \\[uniline-hydra-arrows/uniline-insert-fw-square]	squares  □ ■ ◇ ◆ ◊
 │ \\[uniline-hydra-arrows/uniline-insert-fw-oshape]	circles  · ● ◦ Ø ø
 │ \\[uniline-hydra-arrows/uniline-insert-fw-cross]	crosses  ╳ ÷ × ± ¤
@@ -2794,14 +2794,14 @@ And backup previous settings."
     ["inactive brush"  uniline--set-brush-nil   :style radio :selected (eq uniline--brush nil   )]
     "----"
     ("Insert glyph"
-     ["insert arrow ▷ ▶ → ▹ ▸"  uniline-insert-fw-arrow  :keys "INS a"]
-     ["insert square □ ■ ◇ ◆ ◊" uniline-insert-fw-square :keys "INS s"]
-     ["insert oshape · ● ◦ Ø ø" uniline-insert-fw-oshape :keys "INS o"]
-     ["insert cross ╳ ÷ × ± ¤"  uniline-insert-fw-cross  :keys "INS x"]
-     ["rotate arrow → right"    uniline-rotate-ri→ :keys "INS S-<right>"]
-     ["rotate arrow ↑ up"       uniline-rotate-up↑ :keys "INS S-<up>   "]
-     ["rotate arrow ← left"     uniline-rotate-lf← :keys "INS S-<left> "]
-     ["rotate arrow ↓ down"     uniline-rotate-dw↓ :keys "INS S-<down> "])
+     ["insert arrow ▷ ▶ → ▹ ▸ ↔" uniline-insert-fw-arrow  :keys "INS a"]
+     ["insert square □ ■ ◇ ◆ ◊"  uniline-insert-fw-square :keys "INS s"]
+     ["insert oshape · ● ◦ Ø ø"  uniline-insert-fw-oshape :keys "INS o"]
+     ["insert cross ╳ ÷ × ± ¤"   uniline-insert-fw-cross  :keys "INS x"]
+     ["rotate arrow → right"     uniline-rotate-ri→ :keys "INS S-<right>"]
+     ["rotate arrow ↑ up"        uniline-rotate-up↑ :keys "INS S-<up>   "]
+     ["rotate arrow ← left"      uniline-rotate-lf← :keys "INS S-<left> "]
+     ["rotate arrow ↓ down"      uniline-rotate-dw↓ :keys "INS S-<down> "])
     ("Rectangular region" :active (region-active-p)
      ["move selection right" uniline-move-rect-ri→ :keys "INS <right>"]
      ["move selection left"  uniline-move-rect-lf← :keys "INS <left> "]