5 files changed, 172 insertions, 13 deletions
diff --git a/scene/gui/control.cpp b/scene/gui/control.cpp
index c7ff5980cb..87539ef8f2 100644
--- a/scene/gui/control.cpp
+++ b/scene/gui/control.cpp
@@ -1831,9 +1831,18 @@ bool Control::has_point(const Point2 &p_point) const {
 void Control::set_mouse_filter(MouseFilter p_filter) {
 	ERR_MAIN_THREAD_GUARD;
 	ERR_FAIL_INDEX(p_filter, 3);
+
+	if (data.mouse_filter == p_filter) {
+		return;
+	}
+
 	data.mouse_filter = p_filter;
 	notify_property_list_changed();
 	update_configuration_warnings();
+
+	if (get_viewport()) {
+		get_viewport()->_gui_update_mouse_over();
+	}
 }
 
 Control::MouseFilter Control::get_mouse_filter() const {
@@ -3568,6 +3577,8 @@ void Control::_bind_methods() {
 	BIND_CONSTANT(NOTIFICATION_RESIZED);
 	BIND_CONSTANT(NOTIFICATION_MOUSE_ENTER);
 	BIND_CONSTANT(NOTIFICATION_MOUSE_EXIT);
+	BIND_CONSTANT(NOTIFICATION_MOUSE_ENTER_SELF);
+	BIND_CONSTANT(NOTIFICATION_MOUSE_EXIT_SELF);
 	BIND_CONSTANT(NOTIFICATION_FOCUS_ENTER);
 	BIND_CONSTANT(NOTIFICATION_FOCUS_EXIT);
 	BIND_CONSTANT(NOTIFICATION_THEME_CHANGED);
diff --git a/scene/gui/control.h b/scene/gui/control.h
index abbdc42fa4..db1bd3a346 100644
--- a/scene/gui/control.h
+++ b/scene/gui/control.h
@@ -368,6 +368,8 @@ public:
 		NOTIFICATION_SCROLL_BEGIN = 47,
 		NOTIFICATION_SCROLL_END = 48,
 		NOTIFICATION_LAYOUT_DIRECTION_CHANGED = 49,
+		NOTIFICATION_MOUSE_ENTER_SELF = 60,
+		NOTIFICATION_MOUSE_EXIT_SELF = 61,
 	};
 
 	// Editor plugin interoperability.
diff --git a/scene/main/canvas_item.cpp b/scene/main/canvas_item.cpp
index a350b97bc8..4ee81e5cb0 100644
--- a/scene/main/canvas_item.cpp
+++ b/scene/main/canvas_item.cpp
@@ -462,6 +462,10 @@ void CanvasItem::set_as_top_level(bool p_top_level) {
 	_enter_canvas();
 
 	_notify_transform();
+
+	if (get_viewport()) {
+		get_viewport()->canvas_item_top_level_changed();
+	}
 }
 
 void CanvasItem::_top_level_changed() {
diff --git a/scene/main/viewport.cpp b/scene/main/viewport.cpp
index 2b28f21f57..43bdb1395b 100644
--- a/scene/main/viewport.cpp
+++ b/scene/main/viewport.cpp
@@ -2408,8 +2408,8 @@ void Viewport::_gui_hide_control(Control *p_control) {
 	if (gui.key_focus == p_control) {
 		gui_release_focus();
 	}
-	if (gui.mouse_over == p_control) {
-		_drop_mouse_over();
+	if (gui.mouse_over == p_control || gui.mouse_over_hierarchy.find(p_control) >= 0) {
+		_drop_mouse_over(p_control->get_parent_control());
 	}
 	if (gui.drag_mouse_over == p_control) {
 		gui.drag_mouse_over = nullptr;
@@ -2431,8 +2431,8 @@ void Viewport::_gui_remove_control(Control *p_control) {
 	if (gui.key_focus == p_control) {
 		gui.key_focus = nullptr;
 	}
-	if (gui.mouse_over == p_control) {
-		_drop_mouse_over();
+	if (gui.mouse_over == p_control || gui.mouse_over_hierarchy.find(p_control) >= 0) {
+		_drop_mouse_over(p_control->get_parent_control());
 	}
 	if (gui.drag_mouse_over == p_control) {
 		gui.drag_mouse_over = nullptr;
@@ -2442,6 +2442,94 @@ void Viewport::_gui_remove_control(Control *p_control) {
 	}
 }
 
+void Viewport::canvas_item_top_level_changed() {
+	_gui_update_mouse_over();
+}
+
+void Viewport::_gui_update_mouse_over() {
+	if (gui.mouse_over == nullptr || gui.mouse_over_hierarchy.is_empty()) {
+		return;
+	}
+
+	// Rebuild the mouse over hierarchy.
+	LocalVector<Control *> new_mouse_over_hierarchy;
+	LocalVector<Control *> needs_enter;
+	LocalVector<int> needs_exit;
+
+	CanvasItem *ancestor = gui.mouse_over;
+	bool removing = false;
+	bool reached_top = false;
+	while (ancestor) {
+		Control *ancestor_control = Object::cast_to<Control>(ancestor);
+		if (ancestor_control) {
+			int found = gui.mouse_over_hierarchy.find(ancestor_control);
+			if (found >= 0) {
+				// Remove the node if the propagation chain has been broken or it is now MOUSE_FILTER_IGNORE.
+				if (removing || ancestor_control->get_mouse_filter() == Control::MOUSE_FILTER_IGNORE) {
+					needs_exit.push_back(found);
+				}
+			}
+			if (found == 0) {
+				if (removing) {
+					// Stop if the chain has been broken and the top of the hierarchy has been reached.
+					break;
+				}
+				reached_top = true;
+			}
+			if (!removing && ancestor_control->get_mouse_filter() != Control::MOUSE_FILTER_IGNORE) {
+				new_mouse_over_hierarchy.push_back(ancestor_control);
+				// Add the node if it was not found and it is now not MOUSE_FILTER_IGNORE.
+				if (found < 0) {
+					needs_enter.push_back(ancestor_control);
+				}
+			}
+			if (ancestor_control->get_mouse_filter() == Control::MOUSE_FILTER_STOP) {
+				// MOUSE_FILTER_STOP breaks the propagation chain.
+				if (reached_top) {
+					break;
+				}
+				removing = true;
+			}
+		}
+		if (ancestor->is_set_as_top_level()) {
+			// Top level breaks the propagation chain.
+			if (reached_top) {
+				break;
+			} else {
+				removing = true;
+				ancestor = Object::cast_to<CanvasItem>(ancestor->get_parent());
+				continue;
+			}
+		}
+		ancestor = ancestor->get_parent_item();
+	}
+	if (needs_exit.is_empty() && needs_enter.is_empty()) {
+		return;
+	}
+
+	// Send Mouse Exit Self notification.
+	if (gui.mouse_over && !needs_exit.is_empty() && needs_exit[0] == (int)gui.mouse_over_hierarchy.size() - 1) {
+		gui.mouse_over->notification(Control::NOTIFICATION_MOUSE_EXIT_SELF);
+		gui.mouse_over = nullptr;
+	}
+
+	// Send Mouse Exit notifications.
+	for (int exit_control_index : needs_exit) {
+		gui.mouse_over_hierarchy[exit_control_index]->notification(Control::NOTIFICATION_MOUSE_EXIT);
+	}
+
+	// Update the mouse over hierarchy.
+	gui.mouse_over_hierarchy.resize(new_mouse_over_hierarchy.size());
+	for (int i = 0; i < (int)new_mouse_over_hierarchy.size(); i++) {
+		gui.mouse_over_hierarchy[i] = new_mouse_over_hierarchy[new_mouse_over_hierarchy.size() - 1 - i];
+	}
+
+	// Send Mouse Enter notifications.
+	for (int i = needs_enter.size() - 1; i >= 0; i--) {
+		needs_enter[i]->notification(Control::NOTIFICATION_MOUSE_ENTER);
+	}
+}
+
 Window *Viewport::get_base_window() const {
 	ERR_READ_THREAD_GUARD_V(nullptr);
 	ERR_FAIL_COND_V(!is_inside_tree(), nullptr);
@@ -3069,16 +3157,58 @@ void Viewport::_update_mouse_over(Vector2 p_pos) {
 	// Look for Controls at mouse position.
 	Control *over = gui_find_control(p_pos);
 	bool notify_embedded_viewports = false;
-	if (over != gui.mouse_over) {
-		if (gui.mouse_over) {
-			_drop_mouse_over();
+	if (over != gui.mouse_over || (!over && !gui.mouse_over_hierarchy.is_empty())) {
+		// Find the common ancestor of `gui.mouse_over` and `over`.
+		Control *common_ancestor = nullptr;
+		LocalVector<Control *> over_ancestors;
+
+		if (over) {
+			// Get all ancestors that the mouse is currently over and need an enter signal.
+			CanvasItem *ancestor = over;
+			while (ancestor) {
+				Control *ancestor_control = Object::cast_to<Control>(ancestor);
+				if (ancestor_control) {
+					if (ancestor_control->get_mouse_filter() != Control::MOUSE_FILTER_IGNORE) {
+						int found = gui.mouse_over_hierarchy.find(ancestor_control);
+						if (found >= 0) {
+							common_ancestor = gui.mouse_over_hierarchy[found];
+							break;
+						}
+						over_ancestors.push_back(ancestor_control);
+					}
+					if (ancestor_control->get_mouse_filter() == Control::MOUSE_FILTER_STOP) {
+						// MOUSE_FILTER_STOP breaks the propagation chain.
+						break;
+					}
+				}
+				if (ancestor->is_set_as_top_level()) {
+					// Top level breaks the propagation chain.
+					break;
+				}
+				ancestor = ancestor->get_parent_item();
+			}
+		}
+
+		if (gui.mouse_over || !gui.mouse_over_hierarchy.is_empty()) {
+			// Send Mouse Exit Self and Mouse Exit notifications.
+			_drop_mouse_over(common_ancestor);
 		} else {
 			_drop_physics_mouseover();
 		}
 
-		gui.mouse_over = over;
 		if (over) {
-			over->notification(Control::NOTIFICATION_MOUSE_ENTER);
+			gui.mouse_over = over;
+			gui.mouse_over_hierarchy.reserve(gui.mouse_over_hierarchy.size() + over_ancestors.size());
+
+			// Send Mouse Enter notifications to parents first.
+			for (int i = over_ancestors.size() - 1; i >= 0; i--) {
+				over_ancestors[i]->notification(Control::NOTIFICATION_MOUSE_ENTER);
+				gui.mouse_over_hierarchy.push_back(over_ancestors[i]);
+			}
+
+			// Send Mouse Enter Self notification.
+			gui.mouse_over->notification(Control::NOTIFICATION_MOUSE_ENTER_SELF);
+
 			notify_embedded_viewports = true;
 		}
 	}
@@ -3119,7 +3249,7 @@ void Viewport::_mouse_leave_viewport() {
 	notification(NOTIFICATION_VP_MOUSE_EXIT);
 }
 
-void Viewport::_drop_mouse_over() {
+void Viewport::_drop_mouse_over(Control *p_until_control) {
 	_gui_cancel_tooltip();
 	SubViewportContainer *c = Object::cast_to<SubViewportContainer>(gui.mouse_over);
 	if (c) {
@@ -3131,10 +3261,19 @@ void Viewport::_drop_mouse_over() {
 			v->_mouse_leave_viewport();
 		}
 	}
-	if (gui.mouse_over->is_inside_tree()) {
-		gui.mouse_over->notification(Control::NOTIFICATION_MOUSE_EXIT);
+	if (gui.mouse_over && gui.mouse_over->is_inside_tree()) {
+		gui.mouse_over->notification(Control::NOTIFICATION_MOUSE_EXIT_SELF);
 	}
 	gui.mouse_over = nullptr;
+
+	// Send Mouse Exit notifications to children first. Don't send to p_until_control or above.
+	int notification_until = p_until_control ? gui.mouse_over_hierarchy.find(p_until_control) + 1 : 0;
+	for (int i = gui.mouse_over_hierarchy.size() - 1; i >= notification_until; i--) {
+		if (gui.mouse_over_hierarchy[i]->is_inside_tree()) {
+			gui.mouse_over_hierarchy[i]->notification(Control::NOTIFICATION_MOUSE_EXIT);
+		}
+	}
+	gui.mouse_over_hierarchy.resize(notification_until);
 }
 
 void Viewport::push_input(const Ref<InputEvent> &p_event, bool p_local_coords) {
diff --git a/scene/main/viewport.h b/scene/main/viewport.h
index 65777c973f..82a9bfc438 100644
--- a/scene/main/viewport.h
+++ b/scene/main/viewport.h
@@ -361,6 +361,7 @@ private:
 		BitField<MouseButtonMask> mouse_focus_mask;
 		Control *key_focus = nullptr;
 		Control *mouse_over = nullptr;
+		LocalVector<Control *> mouse_over_hierarchy;
 		Window *subwindow_over = nullptr; // mouse_over and subwindow_over are mutually exclusive. At all times at least one of them is nullptr.
 		Window *windowmanager_window_over = nullptr; // Only used in root Viewport.
 		Control *drag_mouse_over = nullptr;
@@ -429,6 +430,7 @@ private:
 
 	void _gui_remove_control(Control *p_control);
 	void _gui_hide_control(Control *p_control);
+	void _gui_update_mouse_over();
 
 	void _gui_force_drag(Control *p_base, const Variant &p_data, Control *p_control);
 	void _gui_set_drag_preview(Control *p_base, Control *p_control);
@@ -455,7 +457,7 @@ private:
 	void _canvas_layer_add(CanvasLayer *p_canvas_layer);
 	void _canvas_layer_remove(CanvasLayer *p_canvas_layer);
 
-	void _drop_mouse_over();
+	void _drop_mouse_over(Control *p_until_control = nullptr);
 	void _drop_mouse_focus();
 	void _drop_physics_mouseover(bool p_paused_only = false);
 
@@ -494,6 +496,7 @@ protected:
 
 public:
 	void canvas_parent_mark_dirty(Node *p_node);
+	void canvas_item_top_level_changed();
 
 	uint64_t get_processed_events_count() const { return event_count; }