organized UiSystem constructor

MLEM.Startup/MlemGame.cs

@@ -40,15 +40,15 @@ namespace MLEM.Startup {
         /// <summary>
         /// An event that is invoked in <see cref="LoadContent"/>
         /// </summary>
-        public GenericCallback OnLoadContent;
+        public event GenericCallback OnLoadContent;
         /// <summary>
         /// An event that is invoked in <see cref="Update"/>
         /// </summary>
-        public TimeCallback OnUpdate;
+        public event TimeCallback OnUpdate;
         /// <summary>
         /// An event that is invoked in <see cref="Draw"/>
         /// </summary>
-        public TimeCallback OnDraw;
+        public event TimeCallback OnDraw;
 
         /// <summary>
         /// Creates a new MlemGame instance with some default settings

MLEM.Ui/Elements/Element.cs

@@ -15,7 +15,7 @@ namespace MLEM.Ui.Elements {
     /// <summary>
     /// This class represents a generic base class for ui elements of a <see cref="UiSystem"/>.
     /// </summary>
-    public abstract class Element : GenericDataHolder {
+    public abstract class Element : GenericDataHolder, IDisposable {
 
         /// <summary>
         /// A list of all of this element's direct children.
@@ -377,6 +377,11 @@ namespace MLEM.Ui.Elements {
         /// Event that is called when a child is removed from this element using <see cref="RemoveChild"/>
         /// </summary>
         public OtherElementCallback OnChildRemoved;
+        /// <summary>
+        /// Event that is called when this element's <see cref="Dispose"/> method is called, which also happens in <see cref="Finalize"/>.
+        /// This event is useful for unregistering global event handlers when this object should be destroyed.
+        /// </summary>
+        public GenericCallback OnDisposed;
 
         /// <summary>
         /// A style property that contains the selection indicator that is displayed on this element if it is the <see cref="RootElement.SelectedElement"/>
@@ -415,6 +420,11 @@ namespace MLEM.Ui.Elements {
             this.SetSortedChildrenDirty();
         }
 
+        /// <inheritdoc />
+        ~Element() {
+            this.Dispose();
+        }
+
         /// <summary>
         /// Adds a child to this element.
         /// </summary>
@@ -430,7 +440,7 @@ namespace MLEM.Ui.Elements {
             element.AndChildren(e => {
                 e.Root = this.Root;
                 e.System = this.System;
-                this.Root?.OnElementAdded(e);
+                this.Root?.InvokeOnElementAdded(e);
                 this.OnChildAdded?.Invoke(this, e);
             });
             this.SetSortedChildrenDirty();
@@ -451,7 +461,7 @@ namespace MLEM.Ui.Elements {
             element.AndChildren(e => {
                 e.Root = null;
                 e.System = null;
-                this.Root?.OnElementRemoved(e);
+                this.Root?.InvokeOnElementRemoved(e);
                 this.OnChildRemoved?.Invoke(this, e);
             });
             this.SetSortedChildrenDirty();
@@ -618,7 +628,7 @@ namespace MLEM.Ui.Elements {
                 }
 
                 this.area = new RectangleF(pos, newSize);
-                this.System.OnElementAreaUpdated?.Invoke(this);
+                this.System.InvokeOnElementAreaUpdated(this);
 
                 foreach (var child in this.Children)
                     child.ForceUpdateArea();
@@ -626,7 +636,7 @@ namespace MLEM.Ui.Elements {
                 if (this.SetWidthBasedOnChildren || this.SetHeightBasedOnChildren) {
                     Element foundChild = null;
                     var autoSize = this.UnscrolledArea.Size;
-                    
+
                     if (this.SetHeightBasedOnChildren) {
                         var lowest = this.GetLowestChild(e => !e.IsHidden);
                         if (lowest != null) {
@@ -638,7 +648,7 @@ namespace MLEM.Ui.Elements {
                             autoSize.Y = 0;
                         }
                     }
-                    
+
                     if (this.SetWidthBasedOnChildren) {
                         var rightmost = this.GetRightmostChild(e => !e.IsHidden);
                         if (rightmost != null) {
@@ -650,7 +660,7 @@ namespace MLEM.Ui.Elements {
                             autoSize.X = 0;
                         }
                     }
-                    
+
                     if (this.TreatSizeAsMinimum)
                         autoSize = Vector2.Max(autoSize, actualSize);
                     if (!autoSize.Equals(this.UnscrolledArea.Size, 0.01F)) {
@@ -837,7 +847,7 @@ namespace MLEM.Ui.Elements {
         /// </summary>
         /// <param name="time">The game's time</param>
         public virtual void Update(GameTime time) {
-            this.System.OnElementUpdated?.Invoke(this, time);
+            this.System.InvokeOnElementUpdated(this, time);
 
             foreach (var child in this.GetRelevantChildren())
                 if (child.System != null)
@@ -888,9 +898,9 @@ namespace MLEM.Ui.Elements {
         /// <param name="samplerState">The sampler state that is used for drawing</param>
         /// <param name="matrix">The transformation matrix that is used for drawing</param>
         public virtual void Draw(GameTime time, SpriteBatch batch, float alpha, BlendState blendState, SamplerState samplerState, Matrix matrix) {
-            this.System.OnElementDrawn?.Invoke(this, time, batch, alpha);
+            this.System.InvokeOnElementDrawn(this, time, batch, alpha);
             if (this.IsSelected)
-                this.System.OnSelectedElementDrawn?.Invoke(this, time, batch, alpha);
+                this.System.InvokeOnSelectedElementDrawn(this, time, batch, alpha);
 
             foreach (var child in this.GetRelevantChildren()) {
                 if (!child.IsHidden)
@@ -935,6 +945,12 @@ namespace MLEM.Ui.Elements {
             return this.CanBeMoused && this.DisplayArea.Contains(position) ? this : null;
         }
 
+        /// <inheritdoc />
+        public virtual void Dispose() {
+            this.OnDisposed?.Invoke(this);
+            GC.SuppressFinalize(this);
+        }
+
         /// <summary>
         /// Performs the specified action on this element and all of its <see cref="Children"/>
         /// </summary>

MLEM.Ui/Elements/Panel.cs

@@ -15,7 +15,7 @@ namespace MLEM.Ui.Elements {
     /// Additionally, a panel can be set to <see cref="scrollOverflow"/> on construction, which causes all elements that don't fit into the panel to be hidden until scrolled to using a <see cref="ScrollBar"/>.
     /// As this behavior is accomplished using a <see cref="RenderTarget2D"/>, scrolling panels need to have their <see cref="DrawEarly"/> methods called using <see cref="UiSystem.DrawEarly"/>.
     /// </summary>
-    public class Panel : Element, IDisposable {
+    public class Panel : Element {
 
         /// <summary>
         /// The texture that this panel should have, or null if it should be invisible.
@@ -76,11 +76,6 @@ namespace MLEM.Ui.Elements {
             }
         }
 
-        /// <inheritdoc />
-        ~Panel() {
-            this.Dispose();
-        }
-
         /// <inheritdoc />
         public override void ForceUpdateArea() {
             if (this.scrollOverflow) {
@@ -237,12 +232,12 @@ namespace MLEM.Ui.Elements {
         }
 
         /// <inheritdoc />
-        public void Dispose() {
+        public override void Dispose() {
             if (this.renderTarget != null) {
                 this.renderTarget.Dispose();
                 this.renderTarget = null;
             }
-            GC.SuppressFinalize(this);
+            base.Dispose();
         }
 
     }

MLEM.Ui/UiControls.cs

@@ -151,11 +151,11 @@ namespace MLEM.Ui {
                     var selectedNow = mousedNow != null && mousedNow.CanBeSelected ? mousedNow : null;
                     this.SelectElement(this.ActiveRoot, selectedNow);
                     if (mousedNow != null && mousedNow.CanBePressed)
-                        this.System.OnElementPressed?.Invoke(mousedNow);
+                        this.System.InvokeOnElementPressed(mousedNow);
                 } else if (this.Input.IsMouseButtonPressed(MouseButton.Right)) {
                     this.IsAutoNavMode = false;
                     if (mousedNow != null && mousedNow.CanBePressed)
-                        this.System.OnElementSecondaryPressed?.Invoke(mousedNow);
+                        this.System.InvokeOnElementSecondaryPressed(mousedNow);
                 }
             }
 
@@ -165,10 +165,10 @@ namespace MLEM.Ui {
                     if (this.SelectedElement?.Root != null && this.SelectedElement.CanBePressed) {
                         if (this.Input.IsModifierKeyDown(ModifierKey.Shift)) {
                             // secondary action on element using space or enter
-                            this.System.OnElementSecondaryPressed?.Invoke(this.SelectedElement);
+                            this.System.InvokeOnElementSecondaryPressed(this.SelectedElement);
                         } else {
                             // first action on element using space or enter
-                            this.System.OnElementPressed?.Invoke(this.SelectedElement);
+                            this.System.InvokeOnElementPressed(this.SelectedElement);
                         }
                     }
                 } else if (this.Input.IsKeyPressed(Keys.Tab)) {
@@ -189,13 +189,13 @@ namespace MLEM.Ui {
                     var tapped = this.GetElementUnderPos(tap.Position);
                     this.SelectElement(this.ActiveRoot, tapped);
                     if (tapped != null && tapped.CanBePressed)
-                        this.System.OnElementPressed?.Invoke(tapped);
+                        this.System.InvokeOnElementPressed(tapped);
                 } else if (this.Input.GetGesture(GestureType.Hold, out var hold)) {
                     this.IsAutoNavMode = false;
                     var held = this.GetElementUnderPos(hold.Position);
                     this.SelectElement(this.ActiveRoot, held);
                     if (held != null && held.CanBePressed)
-                        this.System.OnElementSecondaryPressed?.Invoke(held);
+                        this.System.InvokeOnElementSecondaryPressed(held);
                 } else if (this.Input.TouchState.Count <= 0) {
                     this.SetTouchedElement(null);
                 } else {
@@ -216,10 +216,10 @@ namespace MLEM.Ui {
             if (this.HandleGamepad) {
                 if (this.GamepadButtons.IsPressed(this.Input, this.GamepadIndex)) {
                     if (this.SelectedElement?.Root != null && this.SelectedElement.CanBePressed)
-                        this.System.OnElementPressed?.Invoke(this.SelectedElement);
+                        this.System.InvokeOnElementPressed(this.SelectedElement);
                 } else if (this.SecondaryGamepadButtons.IsPressed(this.Input, this.GamepadIndex)) {
                     if (this.SelectedElement?.Root != null && this.SelectedElement.CanBePressed)
-                        this.System.OnElementSecondaryPressed?.Invoke(this.SelectedElement);
+                        this.System.InvokeOnElementSecondaryPressed(this.SelectedElement);
                 } else if (this.DownButtons.IsPressed(this.Input, this.GamepadIndex)) {
                     this.HandleGamepadNextElement(Direction2.Down);
                 } else if (this.LeftButtons.IsPressed(this.Input, this.GamepadIndex)) {
@@ -265,14 +265,14 @@ namespace MLEM.Ui {
                 return;
 
             if (selected != null)
-                this.System.OnElementDeselected?.Invoke(selected);
+                this.System.InvokeOnElementDeselected(selected);
             if (element != null) {
-                this.System.OnElementSelected?.Invoke(element);
+                this.System.InvokeOnElementSelected(element);
                 this.selectedElements[root.Name] = element;
             } else {
                 this.selectedElements.Remove(root.Name);
             }
-            this.System.OnSelectedElementChanged?.Invoke(element);
+            this.System.InvokeOnSelectedElementChanged(element);
 
             if (autoNav != null)
                 this.IsAutoNavMode = autoNav.Value;
@@ -285,11 +285,11 @@ namespace MLEM.Ui {
         public void SetMousedElement(Element element) {
             if (element != this.MousedElement) {
                 if (this.MousedElement != null)
-                    this.System.OnElementMouseExit?.Invoke(this.MousedElement);
+                    this.System.InvokeOnElementMouseExit(this.MousedElement);
                 if (element != null)
-                    this.System.OnElementMouseEnter?.Invoke(element);
+                    this.System.InvokeOnElementMouseEnter(element);
                 this.MousedElement = element;
-                this.System.OnMousedElementChanged?.Invoke(element);
+                this.System.InvokeOnMousedElementChanged(element);
             }
         }
 
@@ -300,11 +300,11 @@ namespace MLEM.Ui {
         public void SetTouchedElement(Element element) {
             if (element != this.TouchedElement) {
                 if (this.TouchedElement != null)
-                    this.System.OnElementTouchExit?.Invoke(this.TouchedElement);
+                    this.System.InvokeOnElementTouchExit(this.TouchedElement);
                 if (element != null)
-                    this.System.OnElementTouchEnter?.Invoke(element);
+                    this.System.InvokeOnElementTouchEnter(element);
                 this.TouchedElement = element;
-                this.System.OnTouchedElementChanged?.Invoke(element);
+                this.System.InvokeOnTouchedElementChanged(element);
             }
         }
 

MLEM.Ui/UiSystem.cs

@@ -96,71 +96,71 @@ namespace MLEM.Ui {
         /// <summary>
         /// Event that is invoked after an <see cref="Element"/> is drawn, but before its children are drawn.
         /// </summary>
-        public Element.DrawCallback OnElementDrawn = (e, time, batch, alpha) => e.OnDrawn?.Invoke(e, time, batch, alpha);
+        public event Element.DrawCallback OnElementDrawn;
         /// <summary>
         /// Event that is invoked after the <see cref="RootElement.SelectedElement"/> for each root element is drawn, but before its children are drawn.
         /// </summary>
-        public Element.DrawCallback OnSelectedElementDrawn;
+        public event Element.DrawCallback OnSelectedElementDrawn;
         /// <summary>
         /// Event that is invoked when an <see cref="Element"/> is updated
         /// </summary>
-        public Element.TimeCallback OnElementUpdated = (e, time) => e.OnUpdated?.Invoke(e, time);
+        public event Element.TimeCallback OnElementUpdated;
         /// <summary>
         /// Event that is invoked when an <see cref="Element"/> is pressed with the primary action key
         /// </summary>
-        public Element.GenericCallback OnElementPressed = e => e.OnPressed?.Invoke(e);
+        public event Element.GenericCallback OnElementPressed;
         /// <summary>
         /// Event that is invoked when an <see cref="Element"/> is pressed with the secondary action key
         /// </summary>
-        public Element.GenericCallback OnElementSecondaryPressed = e => e.OnSecondaryPressed?.Invoke(e);
+        public event Element.GenericCallback OnElementSecondaryPressed;
         /// <summary>
         /// Event that is invoked when an <see cref="Element"/> is newly selected using automatic navigation, or after it has been pressed with the mouse.
         /// </summary>
-        public Element.GenericCallback OnElementSelected = e => e.OnSelected?.Invoke(e);
+        public event Element.GenericCallback OnElementSelected;
         /// <summary>
         /// Event that is invoked when an <see cref="Element"/> is deselected during the selection of a new element.
         /// </summary>
-        public Element.GenericCallback OnElementDeselected = e => e.OnDeselected?.Invoke(e);
+        public event Element.GenericCallback OnElementDeselected;
         /// <summary>
         /// Event that is invoked when the mouse enters an <see cref="Element"/>
         /// </summary>
-        public Element.GenericCallback OnElementMouseEnter = e => e.OnMouseEnter?.Invoke(e);
+        public event Element.GenericCallback OnElementMouseEnter;
         /// <summary>
         /// Event that is invoked when the mouse exits an <see cref="Element"/>
         /// </summary>
-        public Element.GenericCallback OnElementMouseExit = e => e.OnMouseExit?.Invoke(e);
+        public event Element.GenericCallback OnElementMouseExit;
         /// <summary>
         /// Event that is invoked when an <see cref="Element"/> starts being touched
         /// </summary>
-        public Element.GenericCallback OnElementTouchEnter = e => e.OnTouchEnter?.Invoke(e);
+        public event Element.GenericCallback OnElementTouchEnter;
         /// <summary>
         /// Event that is invoked when an <see cref="Element"/> stops being touched
         /// </summary>
-        public Element.GenericCallback OnElementTouchExit = e => e.OnTouchExit?.Invoke(e);
+        public event Element.GenericCallback OnElementTouchExit;
         /// <summary>
         /// Event that is invoked when an <see cref="Element"/>'s display area changes
         /// </summary>
-        public Element.GenericCallback OnElementAreaUpdated = e => e.OnAreaUpdated?.Invoke(e);
+        public event Element.GenericCallback OnElementAreaUpdated;
         /// <summary>
         /// Event that is invoked when the <see cref="Element"/> that the mouse is currently over changes
         /// </summary>
-        public Element.GenericCallback OnMousedElementChanged;
+        public event Element.GenericCallback OnMousedElementChanged;
         /// <summary>
         /// Event that is invoked when the <see cref="Element"/> that is being touched changes
         /// </summary>
-        public Element.GenericCallback OnTouchedElementChanged;
+        public event Element.GenericCallback OnTouchedElementChanged;
         /// <summary>
         /// Event that is invoked when the selected <see cref="Element"/> changes, either through automatic navigation, or by pressing on an element with the mouse
         /// </summary>
-        public Element.GenericCallback OnSelectedElementChanged;
+        public event Element.GenericCallback OnSelectedElementChanged;
         /// <summary>
         /// Event that is invoked when a new <see cref="RootElement"/> is added to this ui system
         /// </summary>
-        public RootCallback OnRootAdded;
+        public event RootCallback OnRootAdded;
         /// <summary>
         /// Event that is invoked when a <see cref="RootElement"/> is removed from this ui system
         /// </summary>
-        public RootCallback OnRootRemoved;
+        public event RootCallback OnRootRemoved;
 
         /// <summary>
         /// Creates a new ui system with the given settings.
@@ -172,6 +172,33 @@ namespace MLEM.Ui {
         public UiSystem(Game game, UiStyle style, InputHandler inputHandler = null, bool automaticViewport = true) : base(game) {
             this.Controls = new UiControls(this, inputHandler);
             this.style = style;
+            this.OnElementDrawn += (e, time, batch, alpha) => e.OnDrawn?.Invoke(e, time, batch, alpha);
+            this.OnElementUpdated += (e, time) => e.OnUpdated?.Invoke(e, time);
+            this.OnElementPressed += e => e.OnPressed?.Invoke(e);
+            this.OnElementSecondaryPressed += e => e.OnSecondaryPressed?.Invoke(e);
+            this.OnElementSelected += e => e.OnSelected?.Invoke(e);
+            this.OnElementDeselected += e => e.OnDeselected?.Invoke(e);
+            this.OnElementMouseEnter += e => e.OnMouseEnter?.Invoke(e);
+            this.OnElementMouseExit += e => e.OnMouseExit?.Invoke(e);
+            this.OnElementTouchEnter += e => e.OnTouchEnter?.Invoke(e);
+            this.OnElementTouchExit += e => e.OnTouchExit?.Invoke(e);
+            this.OnElementAreaUpdated += e => e.OnAreaUpdated?.Invoke(e);
+            this.OnMousedElementChanged += e => this.ApplyToAll(t => t.OnMousedElementChanged?.Invoke(t, e));
+            this.OnTouchedElementChanged += e => this.ApplyToAll(t => t.OnTouchedElementChanged?.Invoke(t, e));
+            this.OnSelectedElementChanged += e => this.ApplyToAll(t => t.OnSelectedElementChanged?.Invoke(t, e));
+            this.OnSelectedElementDrawn += (element, time, batch, alpha) => {
+                if (this.Controls.IsAutoNavMode && element.SelectionIndicator.HasValue())
+                    batch.Draw(element.SelectionIndicator, element.DisplayArea, Color.White * alpha, element.Scale / 2);
+            };
+            this.OnElementPressed += e => {
+                if (e.OnPressed != null)
+                    e.ActionSound.Value?.Play();
+            };
+            this.OnElementSecondaryPressed += e => {
+                if (e.OnSecondaryPressed != null)
+                    e.SecondActionSound.Value?.Play();
+            };
+            MlemPlatform.Current?.AddTextInputListener(game.Window, (sender, key, character) => this.ApplyToAll(e => e.OnTextInput?.Invoke(e, key, character)));
 
             if (automaticViewport) {
                 this.Viewport = new Rectangle(Point.Zero, game.Window.ClientBounds.Size);
@@ -183,25 +210,6 @@ namespace MLEM.Ui {
                 };
             }
 
-            if (MlemPlatform.Current != null)
-                MlemPlatform.Current.AddTextInputListener(game.Window, (sender, key, character) => this.ApplyToAll(e => e.OnTextInput?.Invoke(e, key, character)));
-            this.OnMousedElementChanged = e => this.ApplyToAll(t => t.OnMousedElementChanged?.Invoke(t, e));
-            this.OnTouchedElementChanged = e => this.ApplyToAll(t => t.OnTouchedElementChanged?.Invoke(t, e));
-            this.OnSelectedElementChanged = e => this.ApplyToAll(t => t.OnSelectedElementChanged?.Invoke(t, e));
-            this.OnSelectedElementDrawn = (element, time, batch, alpha) => {
-                if (this.Controls.IsAutoNavMode && element.SelectionIndicator.HasValue()) {
-                    batch.Draw(element.SelectionIndicator, element.DisplayArea, Color.White * alpha, element.Scale / 2);
-                }
-            };
-            this.OnElementPressed += e => {
-                if (e.OnPressed != null)
-                    e.ActionSound.Value?.Play();
-            };
-            this.OnElementSecondaryPressed += e => {
-                if (e.OnSecondaryPressed != null)
-                    e.SecondActionSound.Value?.Play();
-            };
-
             this.TextFormatter = new TextFormatter();
             this.TextFormatter.Codes.Add(new Regex("<l(?: ([^>]+))?>"), (f, m, r) => new LinkCode(m, r, 1 / 16F, 0.85F,
                 t => this.Controls.MousedElement is Paragraph.Link l1 && l1.Token == t || this.Controls.TouchedElement is Paragraph.Link l2 && l2.Token == t));
@@ -264,10 +272,11 @@ namespace MLEM.Ui {
             root.Element.AndChildren(e => {
                 e.Root = root;
                 e.System = this;
-                root.OnElementAdded(e);
+                root.InvokeOnElementAdded(e);
                 e.SetAreaDirty();
             });
             this.OnRootAdded?.Invoke(root);
+            root.InvokeOnAddedToUi(this);
             this.SortRoots();
             return root;
         }
@@ -285,10 +294,11 @@ namespace MLEM.Ui {
             root.Element.AndChildren(e => {
                 e.Root = null;
                 e.System = null;
-                root.OnElementRemoved(e);
+                root.InvokeOnElementRemoved(e);
                 e.SetAreaDirty();
             });
             this.OnRootRemoved?.Invoke(root);
+            root.InvokeOnRemovedFromUi(this);
         }
 
         /// <summary>
@@ -331,6 +341,22 @@ namespace MLEM.Ui {
                 root.Element.AndChildren(action);
         }
 
+        internal void InvokeOnElementDrawn(Element element, GameTime time, SpriteBatch batch, float alpha) => this.OnElementDrawn?.Invoke(element, time, batch, alpha);
+        internal void InvokeOnSelectedElementDrawn(Element element, GameTime time, SpriteBatch batch, float alpha) => this.OnSelectedElementDrawn?.Invoke(element, time, batch, alpha);
+        internal void InvokeOnElementUpdated(Element element, GameTime time) => this.OnElementUpdated?.Invoke(element, time);
+        internal void InvokeOnElementAreaUpdated(Element element) => this.OnElementAreaUpdated?.Invoke(element);
+        internal void InvokeOnElementPressed(Element element) => this.OnElementPressed?.Invoke(element);
+        internal void InvokeOnElementSecondaryPressed(Element element) => this.OnElementSecondaryPressed?.Invoke(element);
+        internal void InvokeOnElementSelected(Element element) => this.OnElementSelected?.Invoke(element);
+        internal void InvokeOnElementDeselected(Element element) => this.OnElementDeselected?.Invoke(element);
+        internal void InvokeOnSelectedElementChanged(Element element) => this.OnSelectedElementChanged?.Invoke(element);
+        internal void InvokeOnElementMouseExit(Element element) => this.OnElementMouseExit?.Invoke(element);
+        internal void InvokeOnElementMouseEnter(Element element) => this.OnElementMouseEnter?.Invoke(element);
+        internal void InvokeOnMousedElementChanged(Element element) => this.OnMousedElementChanged?.Invoke(element);
+        internal void InvokeOnElementTouchExit(Element element) => this.OnElementTouchExit?.Invoke(element);
+        internal void InvokeOnElementTouchEnter(Element element) => this.OnElementTouchEnter?.Invoke(element);
+        internal void InvokeOnTouchedElementChanged(Element element) => this.OnTouchedElementChanged?.Invoke(element);
+
         /// <summary>
         /// A delegate used for callbacks that involve a <see cref="RootElement"/>
         /// </summary>
@@ -344,7 +370,7 @@ namespace MLEM.Ui {
     /// Root elements are only used for the element in each element tree that doesn't have a <see cref="MLEM.Ui.Elements.Element.Parent"/>
     /// To create a new root element, use <see cref="UiSystem.Add"/>
     /// </summary>
-    public class RootElement {
+    public class RootElement : GenericDataHolder {
 
         /// <summary>
         /// The name of this root element
@@ -415,11 +441,19 @@ namespace MLEM.Ui {
         /// <summary>
         /// Event that is invoked when a <see cref="Element"/> is added to this root element or any of its children.
         /// </summary>
-        public Element.GenericCallback OnElementAdded;
+        public event Element.GenericCallback OnElementAdded;
         /// <summary>
-        /// Even that is invoked when a <see cref="Element"/> is removed rom this root element of any of its children.
+        /// Event that is invoked when a <see cref="Element"/> is removed rom this root element of any of its children.
         /// </summary>
-        public Element.GenericCallback OnElementRemoved;
+        public event Element.GenericCallback OnElementRemoved;
+        /// <summary>
+        /// Event that is invoked when this <see cref="RootElement"/> gets added to a <see cref="UiSystem"/> in <see cref="UiSystem.Add"/> 
+        /// </summary>
+        public event Action<UiSystem> OnAddedToUi;
+        /// <summary>
+        /// Event that is invoked when this <see cref="RootElement"/> gets removed from a <see cref="UiSystem"/> in <see cref="UiSystem.Remove"/> 
+        /// </summary>
+        public event Action<UiSystem> OnRemovedFromUi;
 
         internal RootElement(string name, Element element, UiSystem system) {
             this.Name = name;
@@ -455,5 +489,10 @@ namespace MLEM.Ui {
             this.Transform = Matrix.CreateScale(scale, scale, 1) * Matrix.CreateTranslation(new Vector3((1 - scale) * (origin ?? this.Element.DisplayArea.Center), 0));
         }
 
+        internal void InvokeOnElementAdded(Element element) => this.OnElementAdded?.Invoke(element);
+        internal void InvokeOnElementRemoved(Element element) => this.OnElementRemoved?.Invoke(element);
+        internal void InvokeOnAddedToUi(UiSystem system) => this.OnAddedToUi?.Invoke(system);
+        internal void InvokeOnRemovedFromUi(UiSystem system) => this.OnRemovedFromUi?.Invoke(system);
+
     }
 }