Add imagescroll feature and capability.

tmux.1

@@ -5194,6 +5194,8 @@ Supports extended keys.
 Supports focus reporting.
 .It hyperlinks
 Supports OSC 8 hyperlinks.
+.It imagescroll
+Moves image content with scroll regions.
 .It ignorefkeys
 Ignore function keys from
 .Xr terminfo 5
@@ -8984,6 +8986,8 @@ These are set automatically if the
 capability is present.
 .It Em \&Hls
 Set or clear a hyperlink annotation.
+.It Em \&Iscrl
+Indicates that the terminal moves image content with scroll regions.
 .It Em \&Nobr
 Tell
 .Nm

tmux.h

@@ -499,6 +499,7 @@ enum tty_code_code {
 	TTYC_IND,
 	TTYC_INDN,
 	TTYC_INVIS,
+	TTYC_ISCRL,
 	TTYC_KCBT,
 	TTYC_KCUB1,
 	TTYC_KCUD1,

tty-features.c

@@ -376,6 +376,17 @@ static const struct tty_feature tty_feature_kittygraphics = {
 	TERM_KITTYGRAPHICS
 };
 
+/* Terminal moves images with scroll regions. */
+static const char *const tty_feature_imagescroll_capabilities[] = {
+	"Iscrl",
+	NULL
+};
+static const struct tty_feature tty_feature_imagescroll = {
+	"imagescroll",
+	tty_feature_imagescroll_capabilities,
+	0
+};
+
 /* Terminal supports the OSC 9;4 progress bar. */
 static const char *const tty_feature_progressbar_capabilities[] = {
 	"Spb=\\E]9;4;%p1%d;%p2%d\\E\\\\",
@@ -406,6 +417,7 @@ static const struct tty_feature *const tty_features[] = {
 	&tty_feature_extkeys,
 	&tty_feature_focus,
 	&tty_feature_ignorefkeys,
+	&tty_feature_imagescroll,
 	&tty_feature_kittygraphics,
 	&tty_feature_margins,
 	&tty_feature_mouse,
@@ -645,6 +657,7 @@ tty_default_features(struct client *c, const char *name, u_int version)
 			      "extkeys,"
 			      "focus,"
 		  	      "hyperlinks,"
+			      "imagescroll,"
 			      "margins,"
 			      "sixel,"
 			      "usstyle"

tty-term.c

@@ -116,6 +116,7 @@ static const struct tty_term_code_entry tty_term_codes[] = {
 	[TTYC_IND] = { TTYCODE_STRING, "ind" },
 	[TTYC_INDN] = { TTYCODE_STRING, "indn" },
 	[TTYC_INVIS] = { TTYCODE_STRING, "invis" },
+	[TTYC_ISCRL] = { TTYCODE_FLAG, "Iscrl" },
 	[TTYC_KCBT] = { TTYCODE_STRING, "kcbt" },
 	[TTYC_KCUB1] = { TTYCODE_STRING, "kcub1" },
 	[TTYC_KCUD1] = { TTYCODE_STRING, "kcud1" },

window-client.c

@@ -89,19 +89,20 @@ static const char *window_client_info_lines[] = {
 	"              #[#{E:tree-mode-border-style},acs]x#[default] "
 	WINDOW_CLIENT_FEATURE(hyperlinks) " "
 	WINDOW_CLIENT_FEATURE(ignorefkeys) " "
-	WINDOW_CLIENT_FEATURE(kittygraphics) " "
+	WINDOW_CLIENT_FEATURE(imagescroll) " "
-	WINDOW_CLIENT_FEATURE(margins),
+	WINDOW_CLIENT_FEATURE(kittygraphics),
 	"              #[#{E:tree-mode-border-style},acs]x#[default] "
+	WINDOW_CLIENT_FEATURE(margins) " "
 	WINDOW_CLIENT_FEATURE(mouse) " "
 	WINDOW_CLIENT_FEATURE(osc7) " "
-	WINDOW_CLIENT_FEATURE(overline) " "
+	WINDOW_CLIENT_FEATURE(overline),
-	WINDOW_CLIENT_FEATURE(progressbar),
 	"              #[#{E:tree-mode-border-style},acs]x#[default] "
+	WINDOW_CLIENT_FEATURE(progressbar) " "
 	WINDOW_CLIENT_FEATURE(rectfill) " "
 	WINDOW_CLIENT_FEATURE(sixel) " "
-	WINDOW_CLIENT_FEATURE(strikethrough) " "
+	WINDOW_CLIENT_FEATURE(strikethrough),
-	WINDOW_CLIENT_FEATURE(sync),
 	"              #[#{E:tree-mode-border-style},acs]x#[default] "
+	WINDOW_CLIENT_FEATURE(sync) " "
 	WINDOW_CLIENT_FEATURE(title) " "
 	WINDOW_CLIENT_FEATURE(usstyle) " "
 	WINDOW_CLIENT_FEATURE(utf8),