macos: remove the ability to bind fn/globe

This was recently introduced a few days ago. Unfortunately, this doesn't
work as expected. The "function" modifier is not actually the fn key
but used by macOS to represent a variety of "functional" key presses.
This breaks other bindings such as #2411.

I can't find a source on the internet that reliably tells me how we
can detect fn key presses, but I do find a number of sources that tell
us we can't.

src/cli/list_keybinds.zig

@@ -133,7 +133,6 @@ fn prettyPrint(alloc: Allocator, keybinds: Config.Keybinds) !u8 {
     const ctrl_style: vaxis.Style = .{ .fg = .{ .index = 2 } };
     const alt_style: vaxis.Style = .{ .fg = .{ .index = 3 } };
     const shift_style: vaxis.Style = .{ .fg = .{ .index = 4 } };
-    const fn_style: vaxis.Style = .{ .fg = .{ .index = 5 } };
 
     var longest_col: usize = 0;
 
@@ -143,10 +142,6 @@ fn prettyPrint(alloc: Allocator, keybinds: Config.Keybinds) !u8 {
 
         var result: vaxis.Window.PrintResult = .{ .col = 0, .row = 0, .overflow = false };
         const trigger = bind.trigger;
-        if (trigger.mods.function) {
-            result = try win.printSegment(.{ .text = "fn   ", .style = fn_style }, .{ .col_offset = result.col });
-            result = try win.printSegment(.{ .text = " + " }, .{ .col_offset = result.col });
-        }
         if (trigger.mods.super) {
             result = try win.printSegment(.{ .text = "super", .style = super_style }, .{ .col_offset = result.col });
             result = try win.printSegment(.{ .text = " + " }, .{ .col_offset = result.col });

src/config/Config.zig

@@ -670,22 +670,13 @@ 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`), `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.
+/// `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.
 ///
-/// 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.
-///   * If you have multiple keyboard layouts active and don't press the
-///     combination fast enough, macOS will switch to the next keyboard
-///     layout.
-///   * 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.
+/// Note that the fn or "globe" key on keyboards are not supported as a
+/// modifier. This is a limitation of the operating systems and GUI toolkits
+/// that Ghostty uses.
 ///
 /// You may also specify multiple triggers separated by `>` to require a
 /// sequence of triggers to activate the action. For example,

src/input/Binding.zig

@@ -901,8 +901,6 @@ pub const Trigger = struct {
                 .{ "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/KeyEncoder.zig

@@ -35,8 +35,6 @@ pub fn encode(
     self: *const KeyEncoder,
     buf: []u8,
 ) ![]const u8 {
-    // log.debug("encode {}", .{self.*});
-
     if (self.kitty_flags.int() != 0) return try self.kitty(buf);
     return try self.legacy(buf);
 }

src/input/key.zig

@@ -89,11 +89,10 @@ 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: u5 = 0,
+    _padding: u6 = 0,
 
     /// Tracks the side that is active for any given modifier. Note
     /// that this doesn't confirm a modifier is pressed; you must check
@@ -131,7 +130,6 @@ pub const Mods = packed struct(Mods.Backing) {
             .ctrl = self.ctrl,
             .alt = self.alt,
             .super = self.super,
-            .function = self.function,
         };
     }