Add display-panes-format to change the top-of-pane text shown with

display-panes.

usr.bin/tmux/cmd-display-panes.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: cmd-display-panes.c,v 1.48 2026/05/31 21:29:41 nicm Exp $ */
+/* $OpenBSD: cmd-display-panes.c,v 1.49 2026/06/08 20:42:39 nicm Exp $ */
 
 /*
  * Copyright (c) 2009 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -76,6 +76,40 @@ cmd_display_panes_put(struct screen_redraw_ctx *ctx,
 	}
 }
 
+static void
+cmd_display_panes_draw_format(struct screen_redraw_ctx *ctx,
+    struct window_pane *wp, u_int xoff, u_int yoff, u_int sx,
+    const struct grid_cell *gc)
+{
+	struct client		*c = ctx->c;
+	struct tty		*tty = &c->tty;
+	struct session		*s = c->session;
+	struct screen		 screen;
+	struct screen_write_ctx	 sctx;
+	struct visible_ranges	*r;
+	struct visible_range	*ri;
+	const char		*format;
+	char			*expanded;
+	u_int			 i, px = ctx->ox + xoff;
+
+	format = options_get_string(s->options, "display-panes-format");
+	expanded = format_single(NULL, format, c, s, s->curw, wp);
+
+	screen_init(&screen, sx, 1, 0);
+	screen_write_start(&sctx, &screen);
+	format_draw(&sctx, gc, sx, expanded, NULL, 0);
+	screen_write_stop(&sctx);
+	free(expanded);
+
+	r = screen_redraw_get_visible_ranges(wp, px, wp->yoff, sx, NULL);
+	for (i = 0; i < r->used; i++) {
+		ri = &r->ranges[i];
+		tty_draw_line(tty, &screen, ri->px - px, 0, ri->nx,
+		    ri->px - ctx->ox, yoff, gc, NULL);
+	}
+	screen_free(&screen);
+}
+
 static void
 cmd_display_panes_draw_pane(struct screen_redraw_ctx *ctx,
     struct window_pane *wp)
@@ -89,8 +123,8 @@ cmd_display_panes_draw_pane(struct screen_redraw_ctx *ctx,
 	u_int			 pane, idx, px, py, i, j, xoff, yoff, sx, sy;
 	u_int			 cx, cy;
 	int			 colour, active_colour;
-	char			 buf[16], lbuf[16], rbuf[16], *ptr;
-	size_t			 len, llen, rlen;
+	char			 buf[16], lbuf[16], *ptr;
+	size_t			 len, llen;
 
 	if (wp->xoff + (int)wp->sx <= ctx->ox ||
 	    wp->xoff >= ctx->ox + (int)ctx->sx ||
@@ -159,7 +193,6 @@ cmd_display_panes_draw_pane(struct screen_redraw_ctx *ctx,
 		bgc.bg = colour;
 	}
 
-	rlen = xsnprintf(rbuf, sizeof rbuf, "%ux%u", wp->sx, wp->sy);
 	if (pane > 9 && pane < 35)
 		llen = xsnprintf(lbuf, sizeof lbuf, "%c", 'a' + (pane - 10));
 	else
@@ -207,13 +240,9 @@ cmd_display_panes_draw_pane(struct screen_redraw_ctx *ctx,
 
 	if (sy <= 6)
 		goto out;
-	tty_attributes(tty, &fgc, &grid_default_cell, NULL, NULL);
-	if (rlen != 0 && sx >= rlen) {
-		cx = xoff + sx - rlen;
-		cy = yoff;
-		cmd_display_panes_put(ctx, wp, cx, cy, rbuf, rlen);
-	}
+	cmd_display_panes_draw_format(ctx, wp, xoff, yoff, sx, &fgc);
 	if (llen != 0) {
+		tty_attributes(tty, &fgc, &grid_default_cell, NULL, NULL);
 		cx = xoff + sx / 2 + len * 3 - llen - 1;
 		cy = yoff + py + 5;
 		cmd_display_panes_put(ctx, wp, cx, cy, lbuf, llen);

usr.bin/tmux/options-table.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: options-table.c,v 1.213 2026/06/07 13:37:39 nicm Exp $ */
+/* $OpenBSD: options-table.c,v 1.214 2026/06/08 20:42:39 nicm Exp $ */
 
 /*
  * Copyright (c) 2011 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -648,6 +648,14 @@ const struct options_table_entry options_table[] = {
 	  .text = "Colour of not active panes for 'display-panes'."
 	},
 
+	{ .name = "display-panes-format",
+	  .type = OPTIONS_TABLE_STRING,
+	  .scope = OPTIONS_TABLE_SESSION,
+	  .default_str = "#[align=right]#{pane_width}x#{pane_height}",
+	  .text = "Format of text shown by 'display-panes', expanded for each "
+		  "pane."
+	},
+
 	{ .name = "display-panes-time",
 	  .type = OPTIONS_TABLE_NUMBER,
 	  .scope = OPTIONS_TABLE_SESSION,

usr.bin/tmux/tmux.1

@@ -1,4 +1,4 @@
-.\" $OpenBSD: tmux.1,v 1.1069 2026/06/08 20:38:54 nicm Exp $
+.\" $OpenBSD: tmux.1,v 1.1070 2026/06/08 20:42:39 nicm Exp $
 .\"
 .\" Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
 .\"
@@ -4798,6 +4798,12 @@ command to show the indicator for the active pane.
 Set the colour used by the
 .Ic display\-panes
 command to show the indicators for inactive panes.
+.It Ic display\-panes\-format Ar format
+Set the
+.Ar format
+of the text shown by the
+.Ic display\-panes
+command, expanded for each pane.
 .It Ic display\-panes\-time Ar time
 Set the time in milliseconds for which the indicators shown by the
 .Ic display\-panes