Configurable right click behavior (#8254)

This MR addresses #4404 following the approach suggested
[here](https://github.com/ghostty-org/ghostty/issues/4404#issuecomment-2708410143).
Implementing the behavior known e.g. from Putty or Windows Terminal.

The following configuration values for `right-click-action` are
provided:
* `context-menu` - Show the context menu.
* `paste` - Paste the contents of the clipboard.
* `copy` - Copy the selected text to the clipboard.
* `copy-and-paste` - Copy the selected text to the clipboard, paste if
nothing is selected.
*  `ignore` - Do nothing, ignore the right-click.

I followed #5935 for getting an idea on where to start. I hope this to
be a temporary solution until "bindable mouse bindings" are introduced.

This is my first time writing Zig code, so I am happy to incorporate any
feedback.

Thank you all very much for your work!

src/Surface.zig

@@ -247,6 +247,7 @@ const DerivedConfig = struct {
     clipboard_paste_protection: bool,
     clipboard_paste_bracketed_safe: bool,
     copy_on_select: configpkg.CopyOnSelect,
+    right_click_action: configpkg.RightClickAction,
     confirm_close_surface: configpkg.ConfirmCloseSurface,
     cursor_click_to_move: bool,
     desktop_notifications: bool,
@@ -314,6 +315,7 @@ const DerivedConfig = struct {
             .clipboard_paste_protection = config.@"clipboard-paste-protection",
             .clipboard_paste_bracketed_safe = config.@"clipboard-paste-bracketed-safe",
             .copy_on_select = config.@"copy-on-select",
+            .right_click_action = config.@"right-click-action",
             .confirm_close_surface = config.@"confirm-close-surface",
             .cursor_click_to_move = config.@"cursor-click-to-move",
             .desktop_notifications = config.@"desktop-notifications",
@@ -1833,6 +1835,32 @@ fn clipboardWrite(self: *const Surface, data: []const u8, loc: apprt.Clipboard)
     };
 }
 
+fn copySelectionToClipboards(
+    self: *Surface,
+    sel: terminal.Selection,
+    clipboards: []const apprt.Clipboard,
+) void {
+    const buf = self.io.terminal.screen.selectionString(self.alloc, .{
+        .sel = sel,
+        .trim = self.config.clipboard_trim_trailing_spaces,
+    }) catch |err| {
+        log.err("error reading selection string err={}", .{err});
+        return;
+    };
+    defer self.alloc.free(buf);
+
+    for (clipboards) |clipboard| self.rt_surface.setClipboardString(
+        buf,
+        clipboard,
+        false,
+    ) catch |err| {
+        log.err(
+            "error setting clipboard string clipboard={} err={}",
+            .{ clipboard, err },
+        );
+    };
+}
+
 /// Set the selection contents.
 ///
 /// This must be called with the renderer mutex held.
@@ -1850,33 +1878,12 @@ fn setSelection(self: *Surface, sel_: ?terminal.Selection) !void {
     const sel = sel_ orelse return;
     if (prev_) |prev| if (sel.eql(prev)) return;
 
-    const buf = self.io.terminal.screen.selectionString(self.alloc, .{
-        .sel = sel,
-        .trim = self.config.clipboard_trim_trailing_spaces,
-    }) catch |err| {
-        log.err("error reading selection string err={}", .{err});
-        return;
-    };
-    defer self.alloc.free(buf);
-
-    // Set the clipboard. This is not super DRY but it is clear what
-    // we're doing for each setting without being clever.
     switch (self.config.copy_on_select) {
         .false => unreachable, // handled above with an early exit
 
         // Both standard and selection clipboards are set.
         .clipboard => {
-            const clipboards: []const apprt.Clipboard = &.{ .standard, .selection };
-            for (clipboards) |clipboard| self.rt_surface.setClipboardString(
-                buf,
-                clipboard,
-                false,
-            ) catch |err| {
-                log.err(
-                    "error setting clipboard string clipboard={} err={}",
-                    .{ clipboard, err },
-                );
-            };
+            self.copySelectionToClipboards(sel, &.{ .standard, .selection });
         },
 
         // The selection clipboard is set if supported, otherwise the standard.
@@ -1885,17 +1892,7 @@ fn setSelection(self: *Surface, sel_: ?terminal.Selection) !void {
                 .selection
             else
                 .standard;
-
-            self.rt_surface.setClipboardString(
-                buf,
-                clipboard,
-                false,
-            ) catch |err| {
-                log.err(
-                    "error setting clipboard string clipboard={} err={}",
-                    .{ clipboard, err },
-                );
-            };
+            self.copySelectionToClipboards(sel, &.{clipboard});
         },
     }
 }
@@ -3582,18 +3579,49 @@ pub fn mouseButtonCallback(
             break :pin pin;
         };
 
-        // If we already have a selection and the selection contains
-        // where we clicked then we don't want to modify the selection.
-        if (self.io.terminal.screen.selection) |prev_sel| {
-            if (prev_sel.contains(screen, pin)) break :sel;
+        switch (self.config.right_click_action) {
+            .ignore => {
+                // Return early to skip clearing the selection.
+                try self.queueRender();
+                return true;
+            },
+            .copy => {
+                if (self.io.terminal.screen.selection) |sel| {
+                    self.copySelectionToClipboards(sel, &.{.standard});
+                }
+            },
+            .@"copy-or-paste" => {
+                if (self.io.terminal.screen.selection) |sel| {
+                    self.copySelectionToClipboards(sel, &.{.standard});
+                } else {
+                    try self.startClipboardRequest(.standard, .paste);
+                }
+            },
+            .paste => {
+                try self.startClipboardRequest(.standard, .paste);
+            },
+            .@"context-menu" => {
+                // If we already have a selection and the selection contains
+                // where we clicked then we don't want to modify the selection.
+                if (self.io.terminal.screen.selection) |prev_sel| {
+                    if (prev_sel.contains(screen, pin)) break :sel;
 
-            // The selection doesn't contain our pin, so we create a new
-            // word selection where we clicked.
+                    // The selection doesn't contain our pin, so we create a new
+                    // word selection where we clicked.
+                }
+
+                const sel = screen.selectWord(pin) orelse break :sel;
+                try self.setSelection(sel);
+                try self.queueRender();
+                return false;
+            },
         }
 
-        const sel = screen.selectWord(pin) orelse break :sel;
-        try self.setSelection(sel);
+        try self.setSelection(null);
         try self.queueRender();
+
+        // Consume the event such that the context menu is not displayed.
+        return true;
     }
 
     return false;

src/config.zig

@@ -19,6 +19,7 @@ pub const ClipboardAccess = Config.ClipboardAccess;
 pub const Command = Config.Command;
 pub const ConfirmCloseSurface = Config.ConfirmCloseSurface;
 pub const CopyOnSelect = Config.CopyOnSelect;
+pub const RightClickAction = Config.RightClickAction;
 pub const CustomShaderAnimation = Config.CustomShaderAnimation;
 pub const FontSyntheticStyle = Config.FontSyntheticStyle;
 pub const FontShapingBreak = Config.FontShapingBreak;

src/config/Config.zig

@@ -1900,6 +1900,19 @@ keybind: Keybinds = .{},
     else => .false,
 },
 
+/// The action to take when the user right-clicks on the terminal surface.
+///
+/// Valid values:
+///   * `context-menu` - Show the context menu.
+///   * `paste` - Paste the contents of the clipboard.
+///   * `copy` - Copy the selected text to the clipboard.
+///   * `copy-or-paste` - If there is a selection, copy the selected text to
+///      the clipboard; otherwise, paste the contents of the clipboard.
+///   * `ignore` - Do nothing, ignore the right-click.
+///
+/// The default value is `context-menu`.
+@"right-click-action": RightClickAction = .@"context-menu",
+
 /// The time in milliseconds between clicks to consider a click a repeat
 /// (double, triple, etc.) or an entirely new single click. A value of zero will
 /// use a platform-specific default. The default on macOS is determined by the
@@ -6709,6 +6722,25 @@ pub const CopyOnSelect = enum {
     clipboard,
 };
 
+/// Options for right-click actions.
+pub const RightClickAction = enum {
+    /// No action is taken on right-click.
+    ignore,
+
+    /// Pastes from the system clipboard.
+    paste,
+
+    /// Copies the selected text to the system clipboard.
+    copy,
+
+    /// Copies the selected text to the system clipboard and
+    /// pastes the clipboard if no text is selected.
+    @"copy-or-paste",
+
+    /// Shows a context menu with options.
+    @"context-menu",
+};
+
 /// Shell integration values
 pub const ShellIntegration = enum {
     none,