I have the tooltip component added so thats a start

src/bin/flappy/main.rs

@@ -224,7 +224,7 @@ fn update_batch(
     mut root: Query<(&mut Transform, &Batch), With<Children>>,
 ) {
     if let Ok((mut t, Batch(idx))) = root.get_mut(trigger.target()) {
-        info!("Updating batch {:?}", idx);
+        debug!("Updating batch {:?}", idx);
         t.translation.x = 500.0 * (*idx) as f32;
     }
     // todo!("Adjust pipe positions");
@@ -239,7 +239,7 @@ fn populate_ground(
     mut commands: Commands,
 ) {
     let Ground(idx) = grounds.get(trigger.target()).unwrap();
-    info!("populating ground {:?}", idx);
+    debug!("populating ground {:?}", idx);
     commands.entity(trigger.target()).insert((
         ground_assets.material.clone(),
         ground_assets.mesh.clone(),

src/debug.rs

@@ -1,4 +1,6 @@
-use std::collections::VecDeque;
+use std::{cmp::Ordering, collections::VecDeque};
+
+use bevy::picking::{backend::HitData, hover::HoverMap};
 
 use super::*;
 
@@ -25,6 +27,7 @@ impl Plugin for DebuggingPlugin {
                             .run_if(on_event::<Pointer<Over>>.or(on_event::<Pointer<Out>>)),
                         tooltip_follow.run_if(any_component_changed::<Window>),
                         sync_resource_to_ui::<ToolTip>.run_if(resource_changed::<ToolTip>),
+                        lock_tooltip.run_if(input_just_pressed(KeyCode::KeyL)),
                         track_fps,
                         sync_resource_to_ui::<Fps>.run_if(resource_changed::<Fps>),
                         track_entity_count,
@@ -231,6 +234,37 @@ fn tooltip_follow(
     }
 }
 
+/// Lok tooltip to entity by inserting the Tooltip component on it
+fn lock_tooltip(
+    q: Query<Option<&ToolTip>>,
+    hover_map: Res<HoverMap>,
+    mut commands: Commands,
+) {
+    hover_map.0.iter().for_each(|(_, hit_data_map)| {
+        if let Some((e, _)) = hit_data_map.iter().min_by(|(_, a), (_, b)| {
+            if a.depth > b.depth {
+                Ordering::Greater
+            } else if a.depth < b.depth {
+                Ordering::Less
+            } else {
+                Ordering::Equal
+            }
+        }) {
+            match q.get(*e) {
+                Ok(None) => {
+                    info!("Adding tooltip to {:?}", e);
+                    commands.entity(*e).insert(ToolTip::default());
+                }
+                Ok(Some(_)) => {
+                    info!("Removing tooltip from {:?}", e);
+                    commands.entity(*e).remove::<ToolTip>();
+                }
+                _ => ()
+            }
+        }
+    });
+}
+
 /// When you hover over a mesh, update the tooltip with some info
 fn hover_mesh(
     mut over_events: EventReader<Pointer<Over>>,