From a40b581fc1df99bba6bfba42c777122ce9bc8f6b Mon Sep 17 00:00:00 2001
From: Simon Tatham <anakin@pobox.com>
Date: Sat, 23 Oct 2021 10:52:11 +0100
Subject: [PATCH] Fix Alt handling in the new shifted-arrow-key support.

As well as affecting the bitmap field in the escape sequence, it was
_also_ having its otherwise standard effect of prefixing Esc to the
whole sequence. It shouldn't do both.
---
 putty.h             | 2 +-
 terminal/terminal.c | 8 +++++---
 unix/window.c       | 8 +++++++-
 windows/window.c    | 7 ++++++-
 4 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/putty.h b/putty.h
index 77301bf8..1719e8db 100644
--- a/putty.h
+++ b/putty.h
@@ -1945,7 +1945,7 @@ typedef enum SmallKeypadKey {
     SKK_HOME, SKK_END, SKK_INSERT, SKK_DELETE, SKK_PGUP, SKK_PGDN,
 } SmallKeypadKey;
 int format_arrow_key(char *buf, Terminal *term, int xkey,
-                     bool shift, bool ctrl, bool alt);
+                     bool shift, bool ctrl, bool alt, bool *consumed_alt);
 int format_function_key(char *buf, Terminal *term, int key_number,
                         bool shift, bool ctrl);
 int format_small_keypad_key(char *buf, Terminal *term, SmallKeypadKey key);
diff --git a/terminal/terminal.c b/terminal/terminal.c
index da255550..dc12755c 100644
--- a/terminal/terminal.c
+++ b/terminal/terminal.c
@@ -7241,16 +7241,18 @@ void term_mouse(Terminal *term, Mouse_Button braw, Mouse_Button bcooked,
     term_schedule_update(term);
 }
 
-static int shift_bitmap(bool shift, bool ctrl, bool alt)
+static int shift_bitmap(bool shift, bool ctrl, bool alt, bool *consumed_alt)
 {
     int bitmap = (shift ? 1 : 0) + (alt ? 2 : 0) + (ctrl ? 4 : 0);
     if (bitmap)
         bitmap++;
+    if (alt && consumed_alt)
+        *consumed_alt = true;
     return bitmap;
 }
 
 int format_arrow_key(char *buf, Terminal *term, int xkey,
-                     bool shift, bool ctrl, bool alt)
+                     bool shift, bool ctrl, bool alt, bool *consumed_alt)
 {
     char *p = buf;
 
@@ -7283,7 +7285,7 @@ int format_arrow_key(char *buf, Terminal *term, int xkey,
                 app_flg = !app_flg;
             break;
           case SHARROW_BITMAP:
-            bitmap = shift_bitmap(shift, ctrl, alt);
+            bitmap = shift_bitmap(shift, ctrl, alt, consumed_alt);
             break;
         }
 
diff --git a/unix/window.c b/unix/window.c
index 9f5948f4..73ff5760 100644
--- a/unix/window.c
+++ b/unix/window.c
@@ -1808,6 +1808,8 @@ gint key_event(GtkWidget *widget, GdkEventKey *event, gpointer data)
 
         switch (event->keyval) {
             int fkey_number;
+            bool consumed_meta_key;
+
           case GDK_KEY_F1: fkey_number = 1; goto numbered_function_key;
           case GDK_KEY_F2: fkey_number = 2; goto numbered_function_key;
           case GDK_KEY_F3: fkey_number = 3; goto numbered_function_key;
@@ -1875,10 +1877,14 @@ gint key_event(GtkWidget *widget, GdkEventKey *event, gpointer data)
           case GDK_KEY_Begin: case GDK_KEY_KP_Begin:
             xkey = 'G'; goto arrow_key;
           arrow_key:
+            consumed_meta_key = false;
             end = 1 + format_arrow_key(output+1, inst->term, xkey,
                                        event->state & GDK_SHIFT_MASK,
                                        event->state & GDK_CONTROL_MASK,
-                                       event->state & GDK_META_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(" - arrow key");
 #endif
diff --git a/windows/window.c b/windows/window.c
index 3b00ad96..a5bad374 100644
--- a/windows/window.c
+++ b/windows/window.c
@@ -4429,6 +4429,8 @@ static int TranslateKey(UINT message, WPARAM wParam, LPARAM lParam,
         }
 
         switch (wParam) {
+            bool consumed_alt;
+
           case VK_NUMPAD0: keypad_key = '0'; goto numeric_keypad;
           case VK_NUMPAD1: keypad_key = '1'; goto numeric_keypad;
           case VK_NUMPAD2: keypad_key = '2'; goto numeric_keypad;
@@ -4536,8 +4538,11 @@ static int TranslateKey(UINT message, WPARAM wParam, LPARAM lParam,
           case VK_LEFT: xkey = 'D'; goto arrow_key;
           case VK_CLEAR: xkey = 'G'; goto arrow_key; /* close enough */
           arrow_key:
+            consumed_alt = false;
             p += format_arrow_key((char *)p, term, xkey, shift_state & 1,
-                                  shift_state & 2, left_alt);
+                                  shift_state & 2, left_alt, &consumed_alt);
+            if (consumed_alt)
+                left_alt = false; /* supersedes the usual prefixing of Esc */
             return p - output;
 
           case VK_RETURN: