seat: handle surface cursor lifetimes explicitly

src/ifs/wl_seat.rs

@@ -879,6 +879,7 @@ impl WlSeatGlobal {
             old.handle_unset();
         }
         if let Some(cursor) = cursor.as_ref() {
+            cursor.clone().handle_set();
             cursor.set_output(&self.output.get());
         }
         self.cursor.set(cursor.clone());

src/ifs/wl_surface.rs

@@ -620,7 +620,6 @@ impl WlSurface {
         let cursor = Rc::new(CursorSurface::new(seat, self));
         track!(self.client, cursor);
         cursor.handle_buffer_change();
-        self.cursors.insert(seat.id(), cursor.clone());
         Ok(cursor)
     }
 

src/ifs/wl_surface/cursor.rs

@@ -123,6 +123,10 @@ impl Cursor for CursorSurface {
         self.surface.set_output(output);
     }
 
+    fn handle_set(self: Rc<Self>) {
+        self.surface.cursors.insert(self.seat.id(), self.clone());
+    }
+
     fn handle_unset(&self) {
         self.surface.cursors.remove(&self.seat.id());
     }