X11 backend: right-click titlebar window menu, matching Wayland's own

Closes the one real gap an X11/Wayland feature-parity audit found this
session (desktop icons, window-position memory, and static exclusive-zone
reservation were already shared or Wayland-only by nature - see
docs/TODO.md's own audit entry for the full breakdown).

MenuAction/ContextMenu (row set, labels, row_at hit-testing) move from
crates/wayland/src/context_menu.rs into crates/core/src/context_menu.rs --
pure state and geometry with nothing Wayland-specific in it, so X11
needing the same rows is shared data, not duplicated logic. The Wayland
crate's own context_menu.rs is now a one-line re-export so every existing
crate::context_menu::... call site keeps working unchanged.

X11 has no compositor-level input dispatch to intercept every click the
way Wayland's input/pointer.rs does, so the X11 side
(crates/x11/src/platform/context_menu.rs, new) draws the menu into its own
small override-redirect popup window and grabs the pointer for the
duration so a click anywhere dismisses it, matching the Wayland backend's
own convention. events.rs's ButtonPress handler now reads the real button
number instead of hardcoding every press as a left click - a real latent
bug (right-clicking a titlebar button would have silently performed its
left-click action).

Live-verified end to end in an isolated Xvfb + srdwm --x11 instance: full
row set including the workspace picker, Minimize runs and closes the
menu, a second window's menu dismisses cleanly on outside click, normal
focus/click behaviour continues working afterward.

See docs/TODO.md for the full investigation and verification narrative.

1 files changed, 8 insertions, 131 deletions

diff --git a/crates/wayland/src/context_menu.rs b/crates/wayland/src/context_menu.rs
index f11e41b..be2afe5 100644
--- a/crates/wayland/src/context_menu.rs
+++ b/crates/wayland/src/context_menu.rs
@@ -1,133 +1,10 @@
-//! Right-click titlebar window menu - the one titlebar interaction
-//! virtually every desktop WM has always offered that srdwm never did.
-//! Right-click on a titlebar previously did nothing at all (the only
-//! right-button behaviour anywhere was the SUPER+right-drag resize
-//! gesture, which needs the modifier held); this gives plain right-click
-//! a real, discoverable action.
+//! Right-click titlebar window menu - the row set and hit-testing now
+//! live in `srdwm_core::context_menu` (shared with the X11 backend, which
+//! needs the exact same rows). This re-export keeps every existing
+//! `crate::context_menu::...` call site in this crate unchanged.
 //!
-//! Deliberately minimal: four fixed actions, no submenus, no live hover
-//! highlight (a nice-to-have that would need the render buffer rebuilt on
-//! every pointer-motion event over the menu - not worth the extra
-//! per-frame cost for a first pass). See `decoration::render_context_menu`
-//! for the actual pixels.
+//! `decoration::render_context_menu` still owns the actual pixels; this
+//! crate has no rendering-specific state of its own to add on top of the
+//! shared struct.
 
-use srdwm_core::{WindowId, WindowManager, TITLEBAR_HEIGHT};
-
-#[derive(Clone, Copy)]
-pub(crate) enum MenuAction {
-    Minimize,
-    ToggleMaximize,
-    ToggleAlwaysOnTop,
-    Close,
-}
-
-pub(crate) struct ContextMenu {
-    pub(crate) window: WindowId,
-    /// Top-left corner, in global (output-independent) space - same frame
-    /// `Window.geometry` and every other `custom_elements` position uses.
-    pub(crate) pos: (i32, i32),
-    pub(crate) width: u32,
-    pub(crate) row_height: u32,
-    pub(crate) items: Vec<(&'static str, MenuAction)>,
-}
-
-const MENU_WIDTH: u32 = 170;
-
-impl ContextMenu {
-    /// Builds the menu for `window`, opening with its top-left corner at
-    /// `pos` (wherever the right-click landed). Labels reflect the
-    /// window's *current* state - "Maximize" flips to "Restore", "Always
-    /// on Top" gets a checkmark prefix once pinned - same convention
-    /// every native window menu uses, rather than a static label that
-    /// silently means the opposite of what it says half the time.
-    pub(crate) fn open(wm: &WindowManager, window: WindowId, pos: (i32, i32)) -> Option<Self> {
-        let w = wm.window(window)?;
-        let maximize_label = if w.maximized { "Restore" } else { "Maximize" };
-        let pin_label = if w.always_on_top { "\u{2713} Always on Top" } else { "Always on Top" };
-        let items = vec![
-            ("Minimize", MenuAction::Minimize),
-            (maximize_label, MenuAction::ToggleMaximize),
-            (pin_label, MenuAction::ToggleAlwaysOnTop),
-            ("Close", MenuAction::Close),
-        ];
-        Some(Self { window, pos, width: MENU_WIDTH, row_height: TITLEBAR_HEIGHT, items })
-    }
-
-    pub(crate) fn height(&self) -> i32 {
-        self.row_height as i32 * self.items.len() as i32
-    }
-
-    /// Which row (if any) global-space point `(x, y)` falls on.
-    pub(crate) fn row_at(&self, x: i32, y: i32) -> Option<usize> {
-        if x < self.pos.0 || x >= self.pos.0 + self.width as i32 {
-            return None;
-        }
-        let rel_y = y - self.pos.1;
-        if rel_y < 0 || rel_y >= self.height() {
-            return None;
-        }
-        Some((rel_y / self.row_height as i32) as usize)
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use srdwm_core::Window;
-
-    fn wm_with_window() -> (WindowManager, WindowId) {
-        let mut wm = WindowManager::new();
-        wm.set_monitors(vec![srdwm_core::Monitor::new(0, "primary", srdwm_core::Rect::new(0, 0, 1920, 1080))]);
-        let id = wm.alloc_window_id();
-        wm.add_window(Window::new(id, "a"));
-        (wm, id)
-    }
-
-    #[test]
-    fn open_labels_maximize_action_by_current_state() {
-        let (mut wm, id) = wm_with_window();
-        let menu = ContextMenu::open(&wm, id, (100, 100)).unwrap();
-        assert_eq!(menu.items[1].0, "Maximize");
-
-        wm.toggle_maximize(id);
-        let menu = ContextMenu::open(&wm, id, (100, 100)).unwrap();
-        assert_eq!(menu.items[1].0, "Restore");
-    }
-
-    #[test]
-    fn open_marks_pinned_state_on_the_always_on_top_row() {
-        let (mut wm, id) = wm_with_window();
-        let menu = ContextMenu::open(&wm, id, (100, 100)).unwrap();
-        assert_eq!(menu.items[2].0, "Always on Top");
-
-        wm.toggle_always_on_top(id);
-        let menu = ContextMenu::open(&wm, id, (100, 100)).unwrap();
-        assert!(menu.items[2].0.starts_with('\u{2713}'), "pinned state must be visible on the label itself");
-    }
-
-    #[test]
-    fn open_returns_none_for_a_window_that_no_longer_exists() {
-        let (wm, id) = wm_with_window();
-        assert!(ContextMenu::open(&wm, id + 999, (0, 0)).is_none());
-    }
-
-    #[test]
-    fn row_at_maps_a_point_to_the_right_row() {
-        let (wm, id) = wm_with_window();
-        let menu = ContextMenu::open(&wm, id, (100, 100)).unwrap();
-        assert_eq!(menu.row_at(150, 100), Some(0), "top of the first row");
-        assert_eq!(menu.row_at(150, 100 + TITLEBAR_HEIGHT as i32 - 1), Some(0), "bottom of the first row");
-        assert_eq!(menu.row_at(150, 100 + TITLEBAR_HEIGHT as i32), Some(1), "top of the second row");
-        assert_eq!(menu.row_at(150, 100 + menu.height() - 1), Some(3), "last row, last pixel");
-    }
-
-    #[test]
-    fn row_at_is_none_outside_the_menus_bounds() {
-        let (wm, id) = wm_with_window();
-        let menu = ContextMenu::open(&wm, id, (100, 100)).unwrap();
-        assert_eq!(menu.row_at(99, 110), None, "just left of the menu");
-        assert_eq!(menu.row_at(100 + MENU_WIDTH as i32, 110), None, "just right of the menu");
-        assert_eq!(menu.row_at(150, 99), None, "just above the menu");
-        assert_eq!(menu.row_at(150, 100 + menu.height()), None, "just below the menu");
-    }
-}
+pub(crate) use srdwm_core::context_menu::{ContextMenu, MenuAction};