Don't update MarginContainer if it already matches its parent size, update TestGame.

TestGame/TestGame.cs

@@ -20,7 +20,7 @@ public class TestGame : Game
         InitializeSystemsDefault();
 
         _uiSystem = new UISystem(Input, ResourceRef<Style>.Empty());
-        _uiSystem.RenderDebugRects = true;
+        // _uiSystem.RenderDebugRects = true;
 
         _particleSystem = new ParticleSystem();
 
@@ -63,19 +63,32 @@ public class TestGame : Game
         Input.AddInputMapping("reload", new IInputAction[] { new KeyInputAction(KeyboardKey.R) });
         _emitterId = _particleSystem.CreateEmitter(Renderer.WindowSize / 2, _fireEffect);
 
-        var button = new Button("Add element", _defaultFontSet, () => { _container.AddChild(new Label("Hello, World!", _defaultFontSet)); });
-        button.Padding = new Margin(8.0f);
+        var addButton = new Button("Add element", _defaultFontSet, () => { _container.AddChild(new Label("Hello, World!", _defaultFontSet)); });
+        addButton.Padding = new Margin(8.0f);
 
-        _buttonContainer.AddChild(button);
+        var removeButton = new Button("Remove element", _defaultFontSet, () =>
+        {
+            if (_container.Children.Count == 0) return;
+            var lastChild = _container.Children.Last();
+            _container.RemoveChild(lastChild);
+        });
 
-        var c = new MarginContainer();
-        c.AddChild(_container);
+        removeButton.Padding = new Margin(8.0f);
 
-        _buttonContainer.AddChild(c);
+        _buttonContainer.AddChild(addButton);
+        _buttonContainer.AddChild(removeButton);
 
-        _root.AddChild(_buttonContainer);
+        var c = new VerticalContainer();
 
-        _uiSystem.AddElement(_root);
+        var m = new MarginContainer();
+        m.AddChild(_container);
+
+        c.AddChild(_buttonContainer);
+        c.AddChild(m);
+
+        _rootFill.AddChild(c);
+
+        _uiSystem.AddElement(_rootFill);
     }
 
 
@@ -86,12 +99,6 @@ public class TestGame : Game
             ResourceManager.Reload();
             _particleSystem!.RestartEmitter(_emitterId);
         }
-
-        if (Input.IsActionPressed("cancel") && _container.Children.Count != 0)
-        {
-            var lastChild = _container.Children.Last();
-            _container.RemoveChild(lastChild);
-        }
     }
 
     protected override void Render(double deltaTime)
@@ -150,6 +157,9 @@ public class TestGame : Game
 
     [NotNull] private Label _label;
 
-    private FillContainer _root = new();
-    private VerticalContainer _buttonContainer = new(16);
+    private FillContainer _rootFill = new();
+    private HorizontalContainer _buttonContainer = new(16)
+    {
+        ConfineToContents = true,
+    };
 }

Voile/Source/UI/Containers/MarginContainer.cs

@@ -65,7 +65,10 @@ public class MarginContainer : Container
         base.OnUpdate();
         if (Parent == null) return;
 
-        Size = Parent.Size;
+        if (Size != Parent.Size)
+        {
+            Size = Parent.Size;
+        }
     }
 
     public override void Arrange()