Improved Inventory / Hand Slots UI (#2965)

Content.Client/UserInterface/HandButton.cs

@@ -1,11 +1,15 @@
 using Content.Shared.GameObjects.Components.Items;
 using Robust.Client.Graphics;
 using Robust.Client.UserInterface.Controls;
+using Robust.Shared.Maths;
 
 namespace Content.Client.UserInterface
 {
     public class HandButton : ItemSlotButton
     {
+        private bool _activeHand;
+        private bool _highlighted;
+
         public HandButton(Texture texture, Texture storageTexture, Texture blockedTexture, HandLocation location) : base(texture, storageTexture)
         {
             Location = location;
@@ -21,5 +25,23 @@ namespace Content.Client.UserInterface
 
         public HandLocation Location { get; }
         public TextureRect Blocked { get; }
+
+        public void SetActiveHand(bool active)
+        {
+            _activeHand = active;
+            UpdateHighlight();
+        }
+
+        public override void Highlight(bool highlight)
+        {
+            _highlighted = highlight;
+            UpdateHighlight();
+        }
+
+        private void UpdateHighlight()
+        {
+            // always stay highlighted if active
+            base.Highlight(_activeHand || _highlighted);
+        }
     }
 }