From fc65e5a7a60c3c968178b8e4323ecc4ad74a75b1 Mon Sep 17 00:00:00 2001
From: Wojciech Figat <wojtek@figat.pl>
Date: Mon, 16 Jan 2023 15:08:57 +0100
Subject: [PATCH] Fix leftover UI control state when it gets
 disabled/hidden/reparented

---
 Source/Engine/UI/GUI/Common/Button.cs    |  9 +++++
 Source/Engine/UI/GUI/ContainerControl.cs | 14 +++++++
 Source/Engine/UI/GUI/Control.cs          | 49 +++++++++++-------------
 3 files changed, 46 insertions(+), 26 deletions(-)

diff --git a/Source/Engine/UI/GUI/Common/Button.cs b/Source/Engine/UI/GUI/Common/Button.cs
index e1f41a5ff..0e0d29615 100644
--- a/Source/Engine/UI/GUI/Common/Button.cs
+++ b/Source/Engine/UI/GUI/Common/Button.cs
@@ -205,6 +205,15 @@ namespace FlaxEngine.GUI
             BorderColorHighlighted = BorderColor;
         }
 
+        /// <inheritdoc />
+        public override void ClearState()
+        {
+            base.ClearState();
+            
+            if (_isPressed)
+                OnPressEnd();
+        }
+
         /// <inheritdoc />
         public override void DrawSelf()
         {
diff --git a/Source/Engine/UI/GUI/ContainerControl.cs b/Source/Engine/UI/GUI/ContainerControl.cs
index 9e226edb5..365889cbf 100644
--- a/Source/Engine/UI/GUI/ContainerControl.cs
+++ b/Source/Engine/UI/GUI/ContainerControl.cs
@@ -750,6 +750,20 @@ namespace FlaxEngine.GUI
             }
         }
 
+        /// <inheritdoc />
+        public override void ClearState()
+        {
+            base.ClearState();
+
+            // Clear state for any nested controls
+            for (int i = 0; i < _children.Count; i++)
+            {
+                var child = _children[i];
+                //if (child.Enabled && child.Enabled)
+                    child.ClearState();
+            }
+        }
+
         /// <summary>
         /// Draw the control and the children.
         /// </summary>
diff --git a/Source/Engine/UI/GUI/Control.cs b/Source/Engine/UI/GUI/Control.cs
index 027dd0267..d7b226cd1 100644
--- a/Source/Engine/UI/GUI/Control.cs
+++ b/Source/Engine/UI/GUI/Control.cs
@@ -131,6 +131,7 @@ namespace FlaxEngine.GUI
                 else
                 {
                     oldParentSize = Float2.Zero;
+                    ClearState();
                 }
 
                 _parent = value;
@@ -214,20 +215,8 @@ namespace FlaxEngine.GUI
                 if (_isEnabled != value)
                 {
                     _isEnabled = value;
-
-                    // Check if control has been disabled
                     if (!_isEnabled)
-                    {
-                        Defocus();
-
-                        // Clear flags
-                        if (_isMouseOver)
-                            OnMouseLeave();
-                        if (_isDragOver)
-                            OnDragLeave();
-                        while (_touchOvers != null && _touchOvers.Count != 0)
-                            OnTouchLeave(_touchOvers[0]);
-                    }
+                        ClearState();
                 }
             }
         }
@@ -259,20 +248,8 @@ namespace FlaxEngine.GUI
                 if (_isVisible != value)
                 {
                     _isVisible = value;
-
-                    // Check on control hide event
                     if (!_isVisible)
-                    {
-                        Defocus();
-
-                        // Clear flags
-                        if (_isMouseOver)
-                            OnMouseLeave();
-                        if (_isDragOver)
-                            OnDragLeave();
-                        while (_touchOvers != null && _touchOvers.Count != 0)
-                            OnTouchLeave(_touchOvers[0]);
-                    }
+                        ClearState();
 
                     OnVisibleChanged();
                     _parent?.PerformLayout();
@@ -453,6 +430,20 @@ namespace FlaxEngine.GUI
         {
         }
 
+        /// <summary>
+        /// Called to clear UI state. For example, removes mouse over state or drag and drop when control gets disabled or hidden (including hierarchy).
+        /// </summary>
+        public virtual void ClearState()
+        {
+            Defocus();
+            if (_isMouseOver)
+                OnMouseLeave();
+            if (_isDragOver)
+                OnDragLeave();
+            while (_touchOvers != null && _touchOvers.Count != 0)
+                OnTouchLeave(_touchOvers[0]);
+        }
+
         #region Focus
 
         /// <summary>
@@ -1338,6 +1329,12 @@ namespace FlaxEngine.GUI
         /// </summary>
         protected virtual void OnVisibleChanged()
         {
+            // Clear state when control gets hidden
+            if (!_isVisible && _isMouseOver)
+            {
+                OnMouseLeave();
+            }
+
             VisibleChanged?.Invoke(this);
         }