Make the function/globe key available as a modifier on macOS

include/ghostty.h

@@ -88,12 +88,13 @@ typedef enum {
   GHOSTTY_MODS_CTRL = 1 << 1,
   GHOSTTY_MODS_ALT = 1 << 2,
   GHOSTTY_MODS_SUPER = 1 << 3,
-  GHOSTTY_MODS_CAPS = 1 << 4,
-  GHOSTTY_MODS_NUM = 1 << 5,
-  GHOSTTY_MODS_SHIFT_RIGHT = 1 << 6,
-  GHOSTTY_MODS_CTRL_RIGHT = 1 << 7,
-  GHOSTTY_MODS_ALT_RIGHT = 1 << 8,
-  GHOSTTY_MODS_SUPER_RIGHT = 1 << 9,
+  GHOSTTY_MODS_FN = 1 << 4,
+  GHOSTTY_MODS_CAPS = 1 << 5,
+  GHOSTTY_MODS_NUM = 1 << 6,
+  GHOSTTY_MODS_SHIFT_RIGHT = 1 << 7,
+  GHOSTTY_MODS_CTRL_RIGHT = 1 << 8,
+  GHOSTTY_MODS_ALT_RIGHT = 1 << 9,
+  GHOSTTY_MODS_SUPER_RIGHT = 1 << 10,
 } ghostty_input_mods_e;
 
 typedef enum {

macos/Sources/App/macOS/AppDelegate.swift

@@ -348,6 +348,11 @@ class AppDelegate: NSObject,
             return
         }
 
+        if (equiv.modifiers.contains(.function)) {
+            // NSMenuItem key equivalent cannot contain function modifiers.
+            return
+        }
+
         menu.keyEquivalent = equiv.key
         menu.keyEquivalentModifierMask = equiv.modifiers
     }

macos/Sources/Ghostty/Ghostty.Input.swift

@@ -14,6 +14,7 @@ extension Ghostty {
         if (mods.rawValue & GHOSTTY_MODS_CTRL.rawValue != 0) { flags.insert(.control) }
         if (mods.rawValue & GHOSTTY_MODS_ALT.rawValue != 0) { flags.insert(.option) }
         if (mods.rawValue & GHOSTTY_MODS_SUPER.rawValue != 0) { flags.insert(.command) }
+        if (mods.rawValue & GHOSTTY_MODS_FN.rawValue != 0) { flags.insert(.function) }
         return flags
     }
 
@@ -25,6 +26,7 @@ extension Ghostty {
         if (flags.contains(.control)) { mods |= GHOSTTY_MODS_CTRL.rawValue }
         if (flags.contains(.option)) { mods |= GHOSTTY_MODS_ALT.rawValue }
         if (flags.contains(.command)) { mods |= GHOSTTY_MODS_SUPER.rawValue }
+        if (flags.contains(.function)) { mods |= GHOSTTY_MODS_FN.rawValue }
         if (flags.contains(.capsLock)) { mods |= GHOSTTY_MODS_CAPS.rawValue }
 
         // Handle sided input. We can't tell that both are pressed in the

macos/Sources/Ghostty/SurfaceView_AppKit.swift

@@ -726,6 +726,7 @@ extension Ghostty {
             case 0x3B, 0x3E: mod = GHOSTTY_MODS_CTRL.rawValue
             case 0x3A, 0x3D: mod = GHOSTTY_MODS_ALT.rawValue
             case 0x37, 0x36: mod = GHOSTTY_MODS_SUPER.rawValue
+            case 0x3F: mod = GHOSTTY_MODS_FN.rawValue
             default: return
             }
 

src/config/Config.zig

@@ -670,9 +670,19 @@ class: ?[:0]const u8 = null,
 ///     translated by any system keyboard layouts. Example: "ctrl+physical:a"
 ///
 /// Valid modifiers are `shift`, `ctrl` (alias: `control`), `alt` (alias: `opt`,
-/// `option`), and `super` (alias: `cmd`, `command`). You may use the modifier
-/// or the alias. When debugging keybinds, the non-aliased modifier will always
-/// be used in output.
+/// `option`), `super` (alias: `cmd`, `command`), and `function` (alias: `fn`,
+/// `globe`). You may use the modifier or the alias. When debugging keybinds,
+/// the non-aliased modifier will always be used in output.
+///
+/// Some notes about the `function` modifier:
+///
+///   * It is only available on macOS.
+///   * It is used by many system shortcuts and Ghostty is not able to
+///     override these shortcuts. If a system shortcut is triggered, the
+///     system shortcut will take precedence.
+///   * Menu items on macOS cannot be bound to the `function` modifier,
+///     so this modifier will work with Ghostty but will not be visible
+///     in the menu.
 ///
 /// You may also specify multiple triggers separated by `>` to require a
 /// sequence of triggers to activate the action. For example,

src/input/Binding.zig

@@ -896,9 +896,13 @@ pub const Trigger = struct {
 
             // Alias modifiers
             const alias_mods = .{
-                .{ "cmd", "super" },    .{ "command", "super" },
-                .{ "opt", "alt" },      .{ "option", "alt" },
+                .{ "cmd", "super" },
+                .{ "command", "super" },
+                .{ "opt", "alt" },
+                .{ "option", "alt" },
                 .{ "control", "ctrl" },
+                .{ "fn", "function" },
+                .{ "globe", "function" },
             };
             inline for (alias_mods) |pair| {
                 if (std.mem.eql(u8, part, pair[0])) {

src/input/key.zig

@@ -89,10 +89,11 @@ pub const Mods = packed struct(Mods.Backing) {
     ctrl: bool = false,
     alt: bool = false,
     super: bool = false,
+    function: bool = false,
     caps_lock: bool = false,
     num_lock: bool = false,
     sides: side = .{},
-    _padding: u6 = 0,
+    _padding: u5 = 0,
 
     /// Tracks the side that is active for any given modifier. Note
     /// that this doesn't confirm a modifier is pressed; you must check