Fix hover tooltip for layout containers

crates/egui/src/containers/tooltip.rs

@@ -335,7 +335,17 @@ impl Tooltip<'_> {
 
         // Fast early-outs:
         if response.enabled() {
-            if !response.hovered() || !response.ctx.input(|i| i.pointer.has_pointer()) {
+            // Hover-only container responses (e.g. `ui.horizontal(...).response`) live below
+            // child widgets. In that case `response.hovered()` can stay false while the pointer
+            // is still inside the container rect. Allow tooltips for these hover-only responses
+            // when the pointer is in the interaction rect and on the same layer.
+            let hovered_or_container_pointer = response.hovered()
+                || (response.sense == Sense::hover()
+                    && response
+                        .ctx
+                        .rect_contains_pointer(response.layer_id, response.interact_rect));
+
+            if !hovered_or_container_pointer || !response.ctx.input(|i| i.pointer.has_pointer()) {
                 return false;
             }
         } else if !response

tests/egui_tests/tests/regression_tests.rs

@@ -141,6 +141,29 @@ fn combobox_should_have_value() {
     );
 }
 
+#[test]
+fn horizontal_response_tooltip_should_show_when_hovering_child() {
+    let mut harness = Harness::builder().with_size((84.0, 64.0)).build_ui(|ui| {
+        ui.style_mut().interaction.tooltip_delay = 0.0;
+        ui.style_mut().interaction.show_tooltips_only_when_still = false;
+
+        ui.horizontal(|ui| {
+            _ = ui.button("A");
+            _ = ui.button("B").on_hover_text("B has a tooltip");
+        })
+        .response
+        .on_hover_text("test");
+    });
+
+    harness.get_by_label("A").hover();
+    harness.run_steps(5);
+    harness.snapshot("horizontal_response_tooltip_should_show_when_hovering_child");
+
+    harness.get_by_label("B").hover();
+    harness.run_steps(5);
+    harness.snapshot("horizontal_response_topmost_tooltip_should_win");
+}
+
 /// This test ensures that `ui.response().interact(...)` works correctly.
 ///
 /// This was broken, because there was an optimization in [`egui::Response::interact`]