Update code examples to the new ControlReference

FlaxEngine/FlaxEngine#3123

Author: mafiesto4

manual/ui/controls/radial-menu.md

@@ -24,12 +24,12 @@ Material assigned to the Radial Menu control can be used to draw the background
 ```cs
 public class RadialMenuUsageExample : Script
 {
-    public Actor ActorRadialMenu;
+    public ControlReference<RadialMenu> ActorRadialMenu;
     private RadialMenu _radialMenu;
 
     public override void OnStart()
     {
-        _radialMenu = ActorRadialMenu.As<UIControl>().Control as RadialMenu;
+        _radialMenu = ActorRadialMenu.Control;
         _radialMenu.Selected += OnOptionSelected;
     }
 

manual/ui/controls/slider.md

@@ -9,13 +9,13 @@ The **Slider** responds to a value changed event from the user to change a value
 Here is a c# example of how to get and use a slider's `ValueChanged` event in a script:
 
 ```cs
-public UIControl SliderUIControl;
+public ControlReference<Slider> Slider;
 private Slider _slider;
 
 public override void OnStart()
 {
-    if (SliderUIControl)
-        _slider = SliderUIControl.Get<Slider>();
+    if (Slider)
+        _slider = Slider.Control;
     if (_slider != null)
         _slider.ValueChanged += OnValueChanged;
 }
@@ -28,6 +28,9 @@ private void OnValueChanged()
 public override void OnDestroy()
 {
     if (_slider != null)
+    {
         _slider.ValueChanged -= OnValueChanged;
+        _slider = null;
+    }
 }
-```
+```

manual/ui/tutorials/create-main-menu.md

@@ -47,7 +47,7 @@ using FlaxEngine.GUI;
 public class MainMenu : Script
 {
 	[Tooltip("The menu buttons.")]
-	public List<UIControl> Buttons;
+	public List<ControlReference<UIControl>> Buttons;
 
 	public override void OnStart()
 	{
@@ -59,7 +59,7 @@ public class MainMenu : Script
 
 		foreach (var button in Buttons)
 		{
-			button.Get<Button>().ButtonClicked += OnButtonClicked;
+			button.Control.ButtonClicked += OnButtonClicked;
 		}
 	}
 

manual/ui/tutorials/create-ui.md

@@ -46,30 +46,31 @@ namespace Game
 		public float Health { get; set; } = 100.0f;
 
 		[Tooltip("Reference to the player health progress bar control")]
-		public UIControl HealthBar { get; set; }
+		public ControlReference<ProgressBar> HealthBar { get; set; }
 
 		private ProgressBar _healthBar;
 
 		public override void OnStart()
 		{
-			if (HealthBar == null || !HealthBar.Is<ProgressBar>())
+			// Cache health bar control
+			_healthBar = HealthBar.Control;
+			if (_healthBar == null)
 			{
-				Debug.LogError("Missing or invalid health bar control");
+				Debug.LogError("Missing health bar control");
 				return;
 			}
-
-			_healthBar = HealthBar.Get<ProgressBar>();
 		}
 
 		public override void OnUpdate()
 		{
+			// Control the health value with keys
 			if (Input.GetKey(KeyboardKeys.Q))
 				Health -= 5;
-
 			if (Input.GetKey(KeyboardKeys.E))
 				Health += 5;
-
 			Health = Mathf.Clamp(Health, 0, 100);
+
+			// Update the progress bar
 			_healthBar.Value = Health;
 		}
 	}