Drag changes (#2487)

* Drag changes

* Higlights only show near cursor
* Don't highlight un-droppable entities
* Fixes invalid highlights issue

* Also the scanner

* 2 months fix

* Address reviews

Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Content.Shared/GameObjects/Components/Movement/SharedClimbableComponent.cs

@@ -1,11 +1,34 @@
-using Robust.Shared.GameObjects;
+using Content.Shared.GameObjects.EntitySystems;
+using Content.Shared.Interfaces.GameObjects.Components;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Serialization;
+using Robust.Shared.ViewVariables;
 
 namespace Content.Shared.GameObjects.Components.Movement
 {
     public interface IClimbable { };
 
-    public class SharedClimbableComponent : Component, IClimbable
+    public abstract class SharedClimbableComponent : Component, IClimbable, IDragDropOn
     {
         public sealed override string Name => "Climbable";
+
+        /// <summary>
+        ///     The range from which this entity can be climbed.
+        /// </summary>
+        [ViewVariables]
+        protected float Range;
+
+        public override void ExposeData(ObjectSerializer serializer)
+        {
+            base.ExposeData(serializer);
+            serializer.DataField(ref Range, "range", SharedInteractionSystem.InteractionRange / 1.4f);
+        }
+
+        public virtual bool CanDragDropOn(DragDropEventArgs eventArgs)
+        {
+            return eventArgs.Dragged.HasComponent<SharedClimbingComponent>();
+        }
+
+        public abstract bool DragDropOn(DragDropEventArgs eventArgs);
     }
 }