New function-key mode similar to modern xterm.

This is the same as the previous FUNKY_XTERM mode if you don't press
any modifier keys, but now Shift or Ctrl or Alt with function keys
adds an extra bitmap parameter. The bitmaps are the same as the ones
used by the new SHARROW_BITMAP arrow key mode.

config.c

@@ -2010,12 +2010,18 @@ void setup_config_box(struct controlbox *b, bool midsession,
                       conf_radiobutton_bool_handler,
                       I(CONF_rxvt_homeend),
                       "Standard", I(false), "rxvt", I(true), NULL);
-    ctrl_radiobuttons(s, "The Function keys and keypad", 'f', 3,
+    ctrl_radiobuttons(s, "The Function keys and keypad", 'f', 4,
                       HELPCTX(keyboard_funkeys),
                       conf_radiobutton_handler,
                       I(CONF_funky_type),
-                      "ESC[n~", I(0), "Linux", I(1), "Xterm R6", I(2),
-                      "VT400", I(3), "VT100+", I(4), "SCO", I(5), NULL);
+                      "ESC[n~", I(FUNKY_TILDE),
+                      "Linux", I(FUNKY_LINUX),
+                      "Xterm R6", I(FUNKY_XTERM),
+                      "VT400", I(FUNKY_VT400),
+                      "VT100+", I(FUNKY_VT100P),
+                      "SCO", I(FUNKY_SCO),
+                      "Xterm 216+", I(FUNKY_XTERM_216),
+                      NULL);
     ctrl_radiobuttons(s, "Shift/Ctrl/Alt with the arrow keys", 'w', 2,
                       HELPCTX(keyboard_sharrow),
                       conf_radiobutton_handler,

doc/config.but

@@ -596,6 +596,15 @@ through to \c{ESC [j}.  With control they generate \c{ESC [k} through
 to \c{ESC [v}, and with shift and control together they generate
 \c{ESC [w} through to \c{ESC [\{}.
 
+\b In \I{xterm}Xterm 216 mode, the unshifted function keys behave the
+same as Xterm R6 mode. But pressing a function key together with Shift
+or Alt or Ctrl generates a different sequence containing an extra
+numeric parameter of the form (1 for Shift) + (2 for Alt) + (4 for
+Ctrl) + 1. For F1-F4, the basic sequences like \c{ESC OP} become
+\cw{ESC [1;}\e{bitmap}\cw{P} and similar; for F5 and above,
+\cw{ESC[}\e{index}\cw{~} becomes
+\cw{ESC[}\e{index}\cw{;}\e{bitmap}\cw{~}.
+
 If you don't know what any of this means, you probably don't need to
 fiddle with it.
 

putty.h

@@ -530,7 +530,8 @@ enum {
     FUNKY_XTERM,
     FUNKY_VT400,
     FUNKY_VT100P,
-    FUNKY_SCO
+    FUNKY_SCO,
+    FUNKY_XTERM_216
 };
 
 enum {
@@ -1947,7 +1948,7 @@ typedef enum SmallKeypadKey {
 int format_arrow_key(char *buf, Terminal *term, int xkey,
                      bool shift, bool ctrl, bool alt, bool *consumed_alt);
 int format_function_key(char *buf, Terminal *term, int key_number,
-                        bool shift, bool ctrl);
+                        bool shift, bool ctrl, bool alt, bool *consumed_alt);
 int format_small_keypad_key(char *buf, Terminal *term, SmallKeypadKey key);
 int format_numeric_keypad_key(char *buf, Terminal *term, char key,
                               bool shift, bool ctrl);

terminal/terminal.c

@@ -7301,7 +7301,7 @@ int format_arrow_key(char *buf, Terminal *term, int xkey,
 }
 
 int format_function_key(char *buf, Terminal *term, int key_number,
-                        bool shift, bool ctrl)
+                        bool shift, bool ctrl, bool alt, bool *consumed_alt)
 {
     char *p = buf;
 
@@ -7314,7 +7314,14 @@ int format_function_key(char *buf, Terminal *term, int key_number,
     assert(key_number > 0);
     assert(key_number < lenof(key_number_to_tilde_code));
 
-    int index = (shift && key_number <= 10) ? key_number + 10 : key_number;
+    int index = key_number;
+    if (term->funky_type != FUNKY_XTERM_216) {
+        if (shift && index <= 10) {
+            shift = false;
+            index += 10;
+        }
+    }
+
     int code = key_number_to_tilde_code[index];
 
     if (term->funky_type == FUNKY_SCO) {
@@ -7338,13 +7345,28 @@ int format_function_key(char *buf, Terminal *term, int key_number,
             p += sprintf(p, "\x1BO%c", code + 'P' - 11 - offt);
     } else if (term->funky_type == FUNKY_LINUX && code >= 11 && code <= 15) {
         p += sprintf(p, "\x1B[[%c", code + 'A' - 11);
-    } else if (term->funky_type == FUNKY_XTERM && code >= 11 && code <= 14) {
+    } else if ((term->funky_type == FUNKY_XTERM ||
+                term->funky_type == FUNKY_XTERM_216) &&
+               code >= 11 && code <= 14) {
         if (term->vt52_mode)
             p += sprintf(p, "\x1B%c", code + 'P' - 11);
-        else
-            p += sprintf(p, "\x1BO%c", code + 'P' - 11);
+        else {
+            int bitmap = 0;
+            if (term->funky_type == FUNKY_XTERM_216)
+                bitmap = shift_bitmap(shift, ctrl, alt, consumed_alt);
+            if (bitmap)
+                p += sprintf(p, "\x1B[1;%d%c", bitmap, code + 'P' - 11);
+            else
+                p += sprintf(p, "\x1BO%c", code + 'P' - 11);
+        }
     } else {
-        p += sprintf(p, "\x1B[%d~", code);
+        int bitmap = 0;
+        if (term->funky_type == FUNKY_XTERM_216)
+            bitmap = shift_bitmap(shift, ctrl, alt, consumed_alt);
+        if (bitmap)
+            p += sprintf(p, "\x1B[%d;%d~", code, bitmap);
+        else
+            p += sprintf(p, "\x1B[%d~", code);
     }
 
     return p - buf;

unix/window.c

@@ -1831,9 +1831,14 @@ gint key_event(GtkWidget *widget, GdkEventKey *event, gpointer data)
           case GDK_KEY_F19: fkey_number = 19; goto numbered_function_key;
           case GDK_KEY_F20: fkey_number = 20; goto numbered_function_key;
           numbered_function_key:
+            consumed_meta_key = false;
             end = 1 + format_function_key(output+1, inst->term, fkey_number,
                                           event->state & GDK_SHIFT_MASK,
-                                          event->state & GDK_CONTROL_MASK);
+                                          event->state & GDK_CONTROL_MASK,
+                                          event->state & inst->meta_mod_mask,
+                                          &consumed_meta_key);
+            if (consumed_meta_key)
+                start = 1; /* supersedes the usual prefixing of Esc */
 #ifdef KEY_EVENT_DIAGNOSTICS
             debug(" - function key F%d", fkey_number);
 #endif

windows/window.c

@@ -4512,8 +4512,12 @@ static int TranslateKey(UINT message, WPARAM wParam, LPARAM lParam,
           case VK_F19: fkey_number = 19; goto numbered_function_key;
           case VK_F20: fkey_number = 20; goto numbered_function_key;
           numbered_function_key:
+            consumed_alt = false;
             p += format_function_key((char *)p, term, fkey_number,
-                                     shift_state & 1, shift_state & 2);
+                                     shift_state & 1, shift_state & 2,
+                                     left_alt, &consumed_alt);
+            if (consumed_alt)
+                left_alt = false; /* supersedes the usual prefixing of Esc */
             return p - output;
 
             SmallKeypadKey sk_key;