Add focus history and Alt-Tab window switching

compositor/src/handlers/mod.rs

@@ -59,6 +59,16 @@ impl SeatHandler for Ferese {
     }
 
     fn focus_changed(&mut self, seat: &Seat<Self>, focused: Option<&WlSurface>) {
+        if let Some(id) = focused.and_then(|surface| {
+            self.window_ids.iter().find_map(|(window, id)| {
+                window
+                    .toplevel()
+                    .is_some_and(|toplevel| toplevel.wl_surface() == surface)
+                    .then_some(*id)
+            })
+        }) {
+            self.focus_history.record(id);
+        }
         if let Some(inhibitor) = self.active_shortcuts_inhibitor.take()
             && inhibitor.is_active()
         {