diff --git a/TestGame/TestGame.cs b/TestGame/TestGame.cs
index df5443b..498e0e7 100644
--- a/TestGame/TestGame.cs
+++ b/TestGame/TestGame.cs
@@ -19,7 +19,7 @@ public class TestGame : Game
     {
         InitializeSystemsDefault();
 
-        _uiSystem = new UISystem(new ResourceRef<Style>(Guid.Empty));
+        _uiSystem = new UISystem(Input, ResourceRef<Style>.Empty());
         _uiSystem.RenderDebugRects = true;
 
         _particleSystem = new ParticleSystem();
@@ -78,12 +78,6 @@ public class TestGame : Game
             var lastChild = _container.Children.Last();
             _container.RemoveChild(lastChild);
         }
-
-        if (Input.IsMouseButtonDown(MouseButton.Left))
-        {
-            var mousePos = Input.GetMousePosition();
-            _container.Size = new Rect(mousePos.X, mousePos.Y);
-        }
     }
 
     protected override void Render(double deltaTime)
diff --git a/Voile/Source/Input/InputAction.cs b/Voile/Source/Input/InputAction.cs
index bd9f0b0..45e7ed1 100644
--- a/Voile/Source/Input/InputAction.cs
+++ b/Voile/Source/Input/InputAction.cs
@@ -33,4 +33,29 @@ namespace Voile.Input
 
         private KeyboardKey _keyboardKey;
     }
+
+    public struct MouseInputAction : IInputAction
+    {
+        public MouseButton MouseButton { get; private set; }
+
+        public MouseInputAction(MouseButton button)
+        {
+            MouseButton = button;
+        }
+
+        public bool IsPressed(InputSystem inputSystem)
+        {
+            return inputSystem.IsMousePressed(MouseButton);
+        }
+
+        public bool IsDown(InputSystem inputSystem)
+        {
+            return inputSystem.IsMouseButtonDown(MouseButton);
+        }
+
+        public bool IsReleased(InputSystem inputSystem)
+        {
+            return inputSystem.IsMouseButtonReleased(MouseButton);
+        }
+    }
 }
\ No newline at end of file
diff --git a/Voile/Source/Input/InputSystem.cs b/Voile/Source/Input/InputSystem.cs
index a8b5584..5168603 100644
--- a/Voile/Source/Input/InputSystem.cs
+++ b/Voile/Source/Input/InputSystem.cs
@@ -101,8 +101,12 @@ namespace Voile.Input
         public abstract bool KeyboardKeyJustReleased(KeyboardKey key);
 
         public abstract int GetCharPressed();
+
+        public abstract bool IsMousePressed(MouseButton button);
         public abstract bool IsMouseButtonDown(MouseButton button);
+        public abstract bool IsMouseButtonReleased(MouseButton button);
         public abstract float GetMouseWheelMovement();
+
         public abstract void SetMousePosition(Vector2 position);
         public abstract Vector2 GetMousePosition();
         public abstract void HideCursor();
diff --git a/Voile/Source/Input/RaylibInputSystem.cs b/Voile/Source/Input/RaylibInputSystem.cs
index af82a74..1391c40 100644
--- a/Voile/Source/Input/RaylibInputSystem.cs
+++ b/Voile/Source/Input/RaylibInputSystem.cs
@@ -34,6 +34,16 @@ namespace Voile.Input
             return Raylib.IsKeyDown(rayKey);
         }
 
+        public override bool IsMousePressed(MouseButton button)
+        {
+            return Raylib.IsMouseButtonPressed((Raylib_cs.MouseButton)button);
+        }
+
+        public override bool IsMouseButtonReleased(MouseButton button)
+        {
+            return Raylib.IsMouseButtonReleased((Raylib_cs.MouseButton)button);
+        }
+
         public override bool IsMouseButtonDown(MouseButton button)
         {
             return Raylib.IsMouseButtonDown((Raylib_cs.MouseButton)button);
diff --git a/Voile/Source/UI/IElement.cs b/Voile/Source/UI/IElement.cs
index 786ce90..fb99770 100644
--- a/Voile/Source/UI/IElement.cs
+++ b/Voile/Source/UI/IElement.cs
@@ -87,5 +87,5 @@ public interface IInputElement
     /// Send an input action to this element.
     /// </summary>
     /// <param name="action">Input action to send.</param>
-    void Input(IInputAction action);
+    void Input(UIInputContext action);
 }
\ No newline at end of file
diff --git a/Voile/Source/UI/UIInputContext.cs b/Voile/Source/UI/UIInputContext.cs
new file mode 100644
index 0000000..b166c65
--- /dev/null
+++ b/Voile/Source/UI/UIInputContext.cs
@@ -0,0 +1,35 @@
+using System.Numerics;
+using Voile.Input;
+
+namespace Voile.UI;
+
+public class UIInputContext
+{
+    public IInputAction Action { get; }
+    public Vector2 MousePosition { get; }
+    public bool MousePressed { get; set; }
+    public bool MouseReleased { get; set; }
+    public bool MouseDown { get; set; }
+
+    public string ActionName { get; }
+
+    public int CharPressed { get; }
+    public bool HasCharInput => CharPressed != 0;
+
+    public bool Handled => _handled;
+
+    /// <summary>
+    /// Marks this context as handled, meaning next elements that will receive it should discard it.
+    /// </summary>
+    public void SetHandled() => _handled = true;
+
+    public UIInputContext(IInputAction action, Vector2 mousePosition, string actionName, int charPressed = 0)
+    {
+        Action = action;
+        MousePosition = mousePosition;
+        ActionName = actionName;
+        CharPressed = charPressed;
+    }
+
+    private bool _handled;
+}
\ No newline at end of file
diff --git a/Voile/Source/UI/UISystem.cs b/Voile/Source/UI/UISystem.cs
index a8bdc92..ddeb463 100644
--- a/Voile/Source/UI/UISystem.cs
+++ b/Voile/Source/UI/UISystem.cs
@@ -1,6 +1,6 @@
 using System.Numerics;
+using Voile.Input;
 using Voile.Rendering;
-using Voile.UI.Containers;
 
 namespace Voile.UI;
 
@@ -10,13 +10,21 @@ public class UISystem : IUpdatableSystem, IRenderableSystem
 
     public bool RenderDebugRects { get; set; }
 
-    public UISystem(ResourceRef<Style> style)
+    public UISystem(InputSystem inputSystem)
     {
+        _style = ResourceRef<Style>.Empty();
+        _input = inputSystem;
+    }
+
+    public UISystem(InputSystem inputSystem, ResourceRef<Style> style)
+    {
+        _input = inputSystem;
         _style = style;
     }
 
-    public UISystem(ResourceRef<Style> style, List<IElement> elements)
+    public UISystem(InputSystem inputSystem, ResourceRef<Style> style, List<IElement> elements)
     {
+        _input = inputSystem;
         _style = style;
         _elements = elements;
     }
@@ -26,6 +34,8 @@ public class UISystem : IUpdatableSystem, IRenderableSystem
 
     public void Update(double deltaTime)
     {
+        HandleInput();
+
         foreach (var element in _elements)
         {
             if (element is not IUpdatableElement updatable) continue;
@@ -58,6 +68,79 @@ public class UISystem : IUpdatableSystem, IRenderableSystem
         }
     }
 
+    private void HandleInput()
+    {
+        int charPressed = _input.GetCharPressed();
+        Vector2 mousePos = _input.GetMousePosition();
+
+        Vector2 currentMousePosition = _input.GetMousePosition();
+
+        foreach (var (actionName, mappings) in InputSystem.InputMappings)
+        {
+            foreach (var action in mappings)
+            {
+                if (action.IsPressed(_input))
+                {
+                    // TODO: specify which mouse button is used in the context.
+                    var context = new UIInputContext(action, mousePos, actionName, charPressed)
+                    {
+                        MouseDown = _input.IsMouseButtonDown(MouseButton.Left),
+                        MouseReleased = _input.IsMouseButtonReleased(MouseButton.Left),
+                        MousePressed = _input.IsMouseButtonReleased(MouseButton.Left),
+                    };
+
+                    if (PropagateInput(_elements, context))
+                        return;
+                }
+            }
+        }
+
+        if (charPressed != 0)
+        {
+            var context = new UIInputContext(new KeyInputAction(KeyboardKey.Null), mousePos, "", charPressed);
+            PropagateInput(_elements, context);
+        }
+
+
+        if (currentMousePosition != _lastMousePosition)
+        {
+            // TODO: specify which mouse button is used in the context.
+            var context = new UIInputContext(new MouseInputAction(MouseButton.Left), mousePos, "", charPressed)
+            {
+                MouseDown = _input.IsMouseButtonDown(MouseButton.Left),
+                MouseReleased = _input.IsMouseButtonReleased(MouseButton.Left),
+                MousePressed = _input.IsMouseButtonReleased(MouseButton.Left),
+            };
+            PropagateInput(_elements, context);
+        }
+    }
+
+    private bool PropagateInput(List<IElement> elements, UIInputContext context)
+    {
+        for (int i = elements.Count - 1; i >= 0; i--)
+        {
+            var element = elements[i];
+
+            if (element is IInputElement inputElement && !inputElement.IgnoreInput)
+            {
+                inputElement.Input(context);
+                _input.SetAsHandled();
+                // return true;
+            }
+
+            if (element is IParentableElement parent)
+            {
+                if (PropagateInput(parent.Children.ToList(), context))
+                    return true;
+            }
+        }
+
+        return false;
+    }
+
     private ResourceRef<Style> _style;
     private List<IElement> _elements = new();
+    private InputSystem _input;
+
+    private Vector2 _lastMousePosition = Vector2.Zero;
 }
\ No newline at end of file
diff --git a/Voile/Source/UI/Widgets/Button.cs b/Voile/Source/UI/Widgets/Button.cs
index 3598f34..8c69090 100644
--- a/Voile/Source/UI/Widgets/Button.cs
+++ b/Voile/Source/UI/Widgets/Button.cs
@@ -33,7 +33,7 @@ public class Button : Widget
         renderer.DrawRectangle(new Vector2(MinimumRect.Width, MinimumRect.Height), new Color(0.25f, 0.25f, 0.25f));
     }
 
-    public override void Input(IInputAction action)
+    protected override void OnInput(UIInputContext action)
     {
 
     }
diff --git a/Voile/Source/UI/Widgets/Label.cs b/Voile/Source/UI/Widgets/Label.cs
index 1a9527b..ba2c06f 100644
--- a/Voile/Source/UI/Widgets/Label.cs
+++ b/Voile/Source/UI/Widgets/Label.cs
@@ -21,7 +21,7 @@ public class Label : Widget
         _fontOverride = fontOverride;
     }
 
-    public override void Input(IInputAction action)
+    protected override void OnInput(UIInputContext action)
     {
         throw new NotImplementedException();
     }
diff --git a/Voile/Source/UI/Widgets/RectangleWidget.cs b/Voile/Source/UI/Widgets/RectangleWidget.cs
index dbae0b4..da6b471 100644
--- a/Voile/Source/UI/Widgets/RectangleWidget.cs
+++ b/Voile/Source/UI/Widgets/RectangleWidget.cs
@@ -8,20 +8,66 @@ public class RectangleWidget : Widget
 {
     public override Rect MinimumRect { get; }
     public Color Color { get; set; } = Color.White;
-    public RectangleWidget(Rect minimumRect, Color color)
+    public RectangleWidget(Rect minimumRect, Color color) : base()
     {
         MinimumRect = minimumRect;
         Color = color;
-    }
 
-    public override void Input(IInputAction action)
-    {
-        throw new NotImplementedException();
+        _defaultColor = color;
+
+        _defaultSize = Size;
+
+        _hoverColor = color.Lightened(0.25f);
     }
 
     public override void Render(RenderSystem renderer, Style style)
     {
         renderer.SetTransform(Position, Vector2.Zero);
-        renderer.DrawRectangle(new Vector2(MinimumRect.Width, MinimumRect.Height), Color);
+        renderer.DrawRectangle(new Vector2(Size.Width, Size.Height), Color);
     }
+
+    protected override void OnInput(UIInputContext inputContext)
+    {
+        if (_defaultSize == Rect.Zero)
+        {
+            _defaultSize = Size;
+        }
+
+        if (_downSize == Rect.Zero)
+        {
+            _downSize = new Rect(Size.Width * 0.75f, Size.Height * 0.75f);
+        }
+
+        var mouseInside = ContainsPoint(inputContext.MousePosition);
+
+        if (mouseInside)
+        {
+            Color = _hoverColor;
+        }
+        else
+        {
+            Color = _defaultColor;
+        }
+
+        if (mouseInside && inputContext.MouseDown)
+        {
+            Size = _downSize;
+        }
+
+        if (mouseInside && inputContext.MouseReleased)
+        {
+            Size = _defaultSize;
+        }
+
+        if (mouseInside && inputContext.MousePressed)
+        {
+            Console.WriteLine("Hello, I was clicked!");
+        }
+    }
+
+    private Color _defaultColor;
+    private Color _hoverColor;
+
+    private Rect _defaultSize = Rect.Zero;
+    private Rect _downSize = Rect.Zero;
 }
\ No newline at end of file
diff --git a/Voile/Source/UI/Widgets/Widget.cs b/Voile/Source/UI/Widgets/Widget.cs
index 5ce7698..01db1cf 100644
--- a/Voile/Source/UI/Widgets/Widget.cs
+++ b/Voile/Source/UI/Widgets/Widget.cs
@@ -16,13 +16,19 @@ public abstract class Widget : IElement, IRenderableElement, IInputElement, IRes
 
     public Widget()
     {
+        MarkDirty();
+    }
 
+    public Widget(Rect size)
+    {
+        Size = size;
+        MarkDirty();
     }
 
     public Widget(Vector2 position)
     {
         Position = position;
-        Size = MinimumRect;
+        MarkDirty();
     }
 
     /// </inheritdoc>
@@ -36,11 +42,17 @@ public abstract class Widget : IElement, IRenderableElement, IInputElement, IRes
     /// <param name="renderer"></param>
     public abstract void Render(RenderSystem renderer, Style style);
 
+    public void Input(UIInputContext context)
+    {
+        if (context.Handled) return;
+        OnInput(context);
+    }
+
     /// <summary>
     /// Called when this widget receives input.
     /// </summary>
     /// <param name="action">An input action this widget received.</param>
-    public abstract void Input(IInputAction action);
+    protected abstract void OnInput(UIInputContext action);
 
     public void Update()
     {