From 41fb515f806370fec207fdd1ad3db476a232b52a Mon Sep 17 00:00:00 2001
From: Ellpeck <me@ellpeck.de>
Date: Tue, 29 Oct 2024 20:28:44 +0100
Subject: [PATCH] Fixed AddedToUi and RemovedFromUi being called for freshly
 added or removed children whose parents are not in a ui system

---
 CHANGELOG.md                |  1 +
 MLEM.Ui/Elements/Element.cs | 10 ++++++----
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 32080ae..63c0e52 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -31,6 +31,7 @@ Additions
 Fixes
 - Fixed tooltips not being bounded correctly for viewports that don't start at the origin
 - Fixed a stack overflow exception when a panel's children have just enough height to cause a scroll bar to appear
+- Fixed AddedToUi and RemovedFromUi being called for freshly added or removed children whose parents are not in a ui system
 
 ### MLEM.Data
 Improvements
diff --git a/MLEM.Ui/Elements/Element.cs b/MLEM.Ui/Elements/Element.cs
index 74f85b8..cf630c8 100644
--- a/MLEM.Ui/Elements/Element.cs
+++ b/MLEM.Ui/Elements/Element.cs
@@ -569,7 +569,8 @@ namespace MLEM.Ui.Elements {
                 index = this.children.Count;
             this.children.Insert(index, element);
             element.Parent = this;
-            element.AndChildren(e => e.AddedToUi(this.System, this.Root));
+            if (this.System != null)
+                element.AndChildren(e => e.AddedToUi(this.System, this.Root));
             this.OnChildAdded?.Invoke(this, element);
             this.SetSortedChildrenDirty();
             element.SetAreaDirty();
@@ -588,7 +589,8 @@ namespace MLEM.Ui.Elements {
             // upwards to us if the element is auto-positioned
             element.SetAreaDirty();
             element.Parent = null;
-            element.AndChildren(e => e.RemovedFromUi());
+            if (this.System != null)
+                element.AndChildren(e => e.RemovedFromUi());
             this.OnChildRemoved?.Invoke(this, element);
             this.SetSortedChildrenDirty();
         }
@@ -1256,7 +1258,7 @@ namespace MLEM.Ui.Elements {
 
         /// <summary>
         /// Called when this element is added to a <see cref="UiSystem"/> and, optionally, a given <see cref="RootElement"/>.
-        /// This method is called in <see cref="AddChild{T}"/> and <see cref="UiSystem.Add"/>.
+        /// This method is called in <see cref="AddChild{T}"/> for a parent whose <see cref="System"/> is set, as well as <see cref="UiSystem.Add"/>.
         /// </summary>
         /// <param name="system">The ui system to add to.</param>
         /// <param name="root">The root element to add to.</param>
@@ -1269,7 +1271,7 @@ namespace MLEM.Ui.Elements {
 
         /// <summary>
         /// Called when this element is removed from a <see cref="UiSystem"/> and <see cref="RootElement"/>.
-        /// This method is called in <see cref="RemoveChild"/> and <see cref="UiSystem.Remove"/>.
+        /// This method is called in <see cref="RemoveChild"/> for a parent whose <see cref="System"/> is set, as well as <see cref="UiSystem.Remove"/>.
         /// </summary>
         protected internal virtual void RemovedFromUi() {
             var root = this.Root;