avm2: Implement DisplayObjectContainer.tabChildren

core/src/avm2/globals/flash/display/Stage.as

@@ -149,7 +149,8 @@ package flash.display {
         }
 
         override public function set tabChildren(value:Boolean):void {
-            super.tabChildren = value;
+            // Docs say that this operation throws IllegalOperationError,
+            // but in reality this call is just ignored.
         }
 
         override public function set tabEnabled(value:Boolean):void {

core/src/avm2/globals/flash/display/display_object_container.rs

@@ -9,10 +9,10 @@ use crate::avm2::object::{Object, TObject};
 use crate::avm2::parameters::ParametersExt;
 use crate::avm2::value::Value;
 use crate::avm2::{ArrayObject, ArrayStorage, Error};
+use crate::avm2_stub_method;
 use crate::context::UpdateContext;
 use crate::display_object::HitTestOptions;
 use crate::display_object::{DisplayObject, TDisplayObject, TDisplayObjectContainer};
-use crate::{avm2_stub_getter, avm2_stub_method, avm2_stub_setter};
 use std::cmp::min;
 
 /// Implements `flash.display.DisplayObjectContainer`'s native instance constructor.
@@ -637,28 +637,31 @@ pub fn set_mouse_children<'gc>(
 
 pub fn get_tab_children<'gc>(
     activation: &mut Activation<'_, 'gc>,
-    _this: Object<'gc>,
+    this: Object<'gc>,
     _args: &[Value<'gc>],
 ) -> Result<Value<'gc>, Error<'gc>> {
-    avm2_stub_getter!(
-        activation,
-        "flash.display.DisplayObjectContainer",
-        "tabChildren"
-    );
-
-    Ok(true.into())
+    if let Some(obj) = this
+        .as_display_object()
+        .and_then(|this| this.as_container())
+    {
+        Ok(Value::Bool(obj.is_tab_children(&mut activation.context)))
+    } else {
+        Ok(Value::Undefined)
+    }
 }
 
 pub fn set_tab_children<'gc>(
     activation: &mut Activation<'_, 'gc>,
-    _this: Object<'gc>,
-    _args: &[Value<'gc>],
+    this: Object<'gc>,
+    args: &[Value<'gc>],
 ) -> Result<Value<'gc>, Error<'gc>> {
-    avm2_stub_setter!(
-        activation,
-        "flash.display.DisplayObjectContainer",
-        "tabChildren"
-    );
+    if let Some(obj) = this
+        .as_display_object()
+        .and_then(|this| this.as_container())
+    {
+        let value = args.get_bool(0);
+        obj.set_tab_children(&mut activation.context, value);
+    }
 
     Ok(Value::Undefined)
 }

core/src/display_object/container.rs

@@ -503,6 +503,9 @@ pub trait TDisplayObjectContainer<'gc>:
         context: &mut UpdateContext<'_, 'gc>,
     ) {
         if !self.is_tab_children(context) {
+            // AS3 docs say that objects with custom ordering (tabIndex set)
+            // are included even when tabChildren is false.
+            // Do not be fooled for that is untrue!
             return;
         }