Before I forget, add warnings on areas without children (should not break anything).

Seen too many users misunderstanding the edit rect is the shape.

scene/2d/collision_object_2d.cpp

@@ -328,6 +328,20 @@ void CollisionObject2D::_update_pickable() {
 		Physics2DServer::get_singleton()->body_set_pickable(rid, pickable);
 }
 
+String CollisionObject2D::get_configuration_warning() const {
+
+	String warning = Node2D::get_configuration_warning();
+
+	if (shapes.empty()) {
+		if (warning == String()) {
+			warning += "\n";
+		}
+		warning += TTR("This node has no children shapes, so it can't interact with the space.\nConsider adding CollisionShape2D or CollisionPolygon2D children nodes to define it's shape.");
+	}
+
+	return warning;
+}
+
 void CollisionObject2D::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("get_rid"), &CollisionObject2D::get_rid);

scene/2d/collision_object_2d.h

@@ -107,6 +107,8 @@ public:
 	void set_pickable(bool p_enabled);
 	bool is_pickable() const;
 
+	String get_configuration_warning() const;
+
 	_FORCE_INLINE_ RID get_rid() const { return rid; }
 
 	CollisionObject2D();

scene/3d/collision_object.cpp

@@ -365,6 +365,20 @@ bool CollisionObject::get_capture_input_on_drag() const {
 	return capture_input_on_drag;
 }
 
+String CollisionObject::get_configuration_warning() const {
+
+	String warning = Spatial::get_configuration_warning();
+
+	if (shapes.empty()) {
+		if (warning == String()) {
+			warning += "\n";
+		}
+		warning += TTR("This node has no children shapes, so it can't interact with the space.\nConsider adding CollisionShape or CollisionPolygon children nodes to define it's shape.");
+	}
+
+	return warning;
+}
+
 CollisionObject::CollisionObject() {
 
 	capture_input_on_drag = false;

scene/3d/collision_object.h

@@ -109,6 +109,8 @@ public:
 
 	_FORCE_INLINE_ RID get_rid() const { return rid; }
 
+	virtual String get_configuration_warning() const;
+
 	CollisionObject();
 	~CollisionObject();
 };