From ff8882a24f44594c871ad849f885bcd895836e73 Mon Sep 17 00:00:00 2001
From: nicm <nicm>
Date: Mon, 26 Jun 2023 07:17:40 +0000
Subject: [PATCH] Add "us" to styles for underscore colour, GitHub issue 3589.

---
 style.c | 15 +++++++++++++++
 tmux.1  |  2 ++
 tty.c   | 13 ++++++++++---
 3 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/style.c b/style.c
index 8407dc68..3d9d317d 100644
--- a/style.c
+++ b/style.c
@@ -77,6 +77,7 @@ style_parse(struct style *sy, const struct grid_cell *base, const char *in)
 		if (strcasecmp(tmp, "default") == 0) {
 			sy->gc.fg = base->fg;
 			sy->gc.bg = base->bg;
+			sy->gc.us = base->us;
 			sy->gc.attr = base->attr;
 			sy->gc.flags = base->flags;
 		} else if (strcasecmp(tmp, "ignore") == 0)
@@ -162,6 +163,13 @@ style_parse(struct style *sy, const struct grid_cell *base, const char *in)
 					sy->gc.bg = base->bg;
 			} else
 				goto error;
+		} else if (end > 3 && strncasecmp(tmp, "us=", 3) == 0) {
+			if ((value = colour_fromstring(tmp + 3)) == -1)
+				goto error;
+			if (value != 8)
+				sy->gc.us = value;
+			else
+				sy->gc.us = base->us;
 		} else if (strcasecmp(tmp, "none") == 0)
 			sy->gc.attr = 0;
 		else if (end > 2 && strncasecmp(tmp, "no", 2) == 0) {
@@ -258,6 +266,11 @@ style_tostring(struct style *sy)
 		    colour_tostring(gc->bg));
 		comma = ",";
 	}
+	if (gc->us != 8) {
+		off += xsnprintf(s + off, sizeof s - off, "%sus=%s", comma,
+		    colour_tostring(gc->us));
+		comma = ",";
+	}
 	if (gc->attr != 0) {
 		xsnprintf(s + off, sizeof s - off, "%s%s", comma,
 		    attributes_tostring(gc->attr));
@@ -287,6 +300,8 @@ style_add(struct grid_cell *gc, struct options *oo, const char *name,
 		gc->fg = sy->gc.fg;
 	if (sy->gc.bg != 8)
 		gc->bg = sy->gc.bg;
+	if (sy->gc.us != 8)
+		gc->us = sy->gc.us;
 	gc->attr |= sy->gc.attr;
 
 	if (ft0 != NULL)
diff --git a/tmux.1 b/tmux.1
index 4881b820..8b76bbac 100644
--- a/tmux.1
+++ b/tmux.1
@@ -5384,6 +5384,8 @@ for the terminal default colour; or a hexadecimal RGB string such as
 .Ql #ffffff .
 .It Ic bg=colour
 Set the background colour.
+.It Ic us=colour
+Set the underscore colour.
 .It Ic none
 Set no attributes (turn off any active attributes).
 .It Xo Ic acs ,
diff --git a/tty.c b/tty.c
index 225d0058..e34b186a 100644
--- a/tty.c
+++ b/tty.c
@@ -483,6 +483,12 @@ tty_update_features(struct tty *tty)
 	if (tty->term->flags & TERM_VT100LIKE)
 		tty_puts(tty, "\033[?7727h");
 
+	/*
+	 * Features might have changed since the first draw during attach. For
+	 * example, this happens when DA responses are received.
+	 */
+	server_redraw_client(c);
+
 	tty_invalidate(tty);
 }
 
@@ -2808,9 +2814,10 @@ tty_check_us(__unused struct tty *tty, struct colour_palette *palette,
 			gc->us = c;
 	}
 
-	/* Underscore colour is set as RGB so convert a 256 colour to RGB. */
-	if (gc->us & COLOUR_FLAG_256)
-		gc->us = colour_256toRGB (gc->us);
+	/* Underscore colour is set as RGB so convert. */
+	gc->us = colour_force_rgb (gc->us);
+	if (gc->us == -1)
+		gc->us = 8;
 }
 
 static void