menu: never activate a row from an earlier frame (#574)

Nav kept the rows of the last frame that drew them. When a title click
closed the popup before its rows drew again, Enter or Space ran the
cached command with its old enabled state. Nav::load now clears the rows,
so the keys act only on rows drawn this frame under the current gate.

crates/menu/src/bar/nav.rs

@@ -120,6 +120,9 @@ impl Nav {
         if top != nav.top {
             nav = Nav { top, tops: std::mem::take(&mut nav.tops), ..Default::default() };
         }
+        // Rows hold the command and enabled state of the frame that drew them. A popup that is
+        // not drawn this frame (closed by a title click) must leave nothing for the keys to run.
+        nav.rows.clear();
         nav
     }
 

crates/menu/src/tests/bar.rs

@@ -10,6 +10,23 @@ use crate::bar::nav::{ARROW, Nav, heading, is_open};
 #[path = "bar_keys.rs"]
 mod keys;
 
+#[test]
+fn rows_from_an_earlier_frame_are_never_activated() {
+    let ctx = egui::Context::default();
+    let id = Id::unique("nav");
+    let row = crate::bar::nav::Row {
+        widget: Id::unique("row"),
+        enabled: true,
+        command: Some(Builtin::Quit.command()),
+        rect: Rect::NOTHING,
+        mnemonic: None,
+    };
+    let mut stale = Nav::default();
+    stale.rows = vec![vec![row]];
+    ctx.data_mut(|d| d.insert_temp(id, stale));
+    assert!(Nav::load(&ctx, id).rows.is_empty(), "rows are this frame's only");
+}
+
 fn item(id: &str, label: &str) -> Item {
     Item::new(id, label)
 }