input: recognize some escape sequences for <Shift+Delete>

Also, hard-bind <Shift+Delete> in the same way as <Backspace>.

This fixes https://savannah.gnu.org/bugs/?54948,
and fixes https://savannah.gnu.org/bugs/?54975.

src/global.c

@@ -1093,6 +1093,7 @@ void shortcut_init(void)
 	add_to_sclist(MMOST, "Enter", KEY_ENTER, do_enter, 0);
 	add_to_sclist(MMOST, "^H", 0, do_backspace, 0);
 	add_to_sclist(MMOST, "Bsp", KEY_BACKSPACE, do_backspace, 0);
+	add_to_sclist(MMOST, "Sh-Del", SHIFT_DELETE, do_backspace, 0);
 	add_to_sclist(MMOST, "^D", 0, do_delete, 0);
 	add_to_sclist(MMOST, "Del", 0, do_delete, 0);
 	/* Make ASCII DEL do a delete when requested, otherwise a backspace. */
@@ -1128,6 +1129,7 @@ void shortcut_init(void)
 	add_to_sclist(MMAIN, "M-G", 0, do_gotolinecolumn_void, 0);
 	add_to_sclist(MMAIN|MHELP|MBROWSER|MLINTER, "^Y", 0, do_page_up, 0);
 	add_to_sclist(MHELP|MBROWSER, "Bsp", KEY_BACKSPACE, do_page_up, 0);
+	add_to_sclist(MHELP|MBROWSER, "Sh-Del", SHIFT_DELETE, do_page_up, 0);
 	add_to_sclist(MMAIN|MHELP|MBROWSER|MLINTER, "PgUp", KEY_PPAGE, do_page_up, 0);
 	add_to_sclist(MMAIN|MHELP|MBROWSER|MLINTER, "^V", 0, do_page_down, 0);
 	add_to_sclist(MHELP|MBROWSER, "Space", 0x20, do_page_down, 0);

src/nano.h

@@ -607,6 +607,7 @@ enum
 #define SHIFT_END 0x456
 #define SHIFT_PAGEUP 0x457
 #define SHIFT_PAGEDOWN 0x458
+#define SHIFT_DELETE 0x45D
 #define SHIFT_TAB 0x45F
 
 #ifdef USE_SLANG

src/winio.c

@@ -602,6 +602,9 @@ int parse_kbinput(WINDOW *win)
 				return SHIFT_TAB;
 			shift_held = TRUE;
 		}
+		/* Is Shift being held while Delete is pressed? */
+		if (modifiers == 0x01 && retval == KEY_DC)
+			return SHIFT_DELETE;
 		/* Are Ctrl and Shift being held while Delete is pressed? */
 		if (modifiers == 0x05 && retval == KEY_DC)
 			return CONTROL_SHIFT_DELETE;
@@ -722,8 +725,8 @@ int parse_kbinput(WINDOW *win)
 		case KEY_C3:    /* PageDown (3) on keypad with NumLock off. */
 			return KEY_NPAGE;
 #ifdef KEY_SDC  /* Slang doesn't support KEY_SDC. */
-		case KEY_SDC:  /* Make a shifted <Del> key do a backspace. */
-			return KEY_BACKSPACE;
+		case KEY_SDC:
+			return SHIFT_DELETE;
 #endif
 #ifdef KEY_SIC  /* Slang doesn't support KEY_SIC. */
 		case KEY_SIC:
@@ -1109,6 +1112,9 @@ int convert_sequence(const int *seq, size_t length, int *consumed)
 #ifndef NANO_TINY
 						if (length > 4 && seq[2] == ';' && seq[4] == '~') {
 							*consumed = 5;
+							if (seq[3] == '2')
+								/* Esc [ 3 ; 2 ~ == Shift-Delete on xterm/Terminal. */
+								return SHIFT_DELETE;
 							if (seq[3] == '3')
 								/* Esc [ 3 ; 3 ~ == Alt-Delete on xterm/rxvt/Eterm/Terminal. */
 								return ALT_DELETE;
@@ -1119,6 +1125,9 @@ int convert_sequence(const int *seq, size_t length, int *consumed)
 								/* Esc [ 3 ; 6 ~ == Ctrl-Shift-Delete on xterm. */
 								return controlshiftdelete;
 						}
+						if (length > 2 && seq[2] == '$')
+							/* Esc [ 3 $ == Shift-Delete on urxvt. */
+							return SHIFT_DELETE;
 						if (length > 2 && seq[2] == '^')
 							/* Esc [ 3 ^ == Ctrl-Delete on urxvt. */
 							return CONTROL_DELETE;

syntax/nanohelp.nanorc

@@ -5,7 +5,7 @@ syntax nanohelp
 
 # Key combos:
 color cyan "\^[]4-8A-Z^\_◀▶▲▼]"  "[◀▶▲▼]"  "\<M-."  "\<F1?[0-9]"
-color cyan "\<(Tab|Sh-Tab|Enter|Ins|Del|Sh-\^Del|Space|Bsp|Up|Down|Left|Right|Home|End|PgUp|PgDn)\>"
+color cyan "\<(Tab|Sh-Tab|Enter|Ins|Del|Sh-\^?Del|Space|Bsp|Up|Down|Left|Right|Home|End|PgUp|PgDn)\>"
 
 # Quoted indicators:
 color brightred "'(\^|M-)'"