How can I create a draggable foldout for editor window?

Unity Editor Interface
1

Hey all I would like to create a draggable foldout for my editor window (or inspector would be fine) like the ones used by the project window and hierarchy.

Here’s the Story :

I have a scriptable object asset and its job is to provide a database for all world (“pickup items”) in my game. if I just add a list to my scriptable object, it as you know will eventually become like a rat’s nest in the inspector. So the idea is to create a makeshift pathing system in the asset class that can be used as a reference to the world item.

The foldouts would then work as the “folders” similarly to how the asset folder foldouts do.

Thanks.

I don’t know if it will help but here’s the world item class that has the field for a path so you can get an understanding of what i’m talking about as far as a pathing system for world items goes.

    [System.Serializable]
    public class WorldItem{
        public string itemName = "", itemPath = "";
        public ItemEnhancementCode[] enhancementCodes = new ItemEnhancementCode[0];
        public float weightPerItem = 0;
        public InventoryItemType itemType = InventoryItemType.Misc;
        public Currency venderCostPer = Currency.zero, venderSellPricePer = Currency.zero;
        public Sprite inventoryImage = null;

        public InventoryItem ToInventoryItem(){
            return ToInventoryItem (1, 0);
        }

        public InventoryItem ToInventoryItem(int ammount){
            return ToInventoryItem (ammount, 0);
        }

        public InventoryItem ToInventoryItem(int ammount, int ammountStolen){
            return new InventoryItem (itemName, ammount, ammountStolen, enhancementCodes, weightPerItem, itemType, venderCostPer, venderSellPricePer);
        }

        public static explicit operator InventoryItem(WorldItem worldItem){
            return worldItem.ToInventoryItem ();
        }
    }
2

Okay so I figured out this much it seems to be a step in the right direction. So I guess the real question is now more about how to operate the GUIStyle.

	public class WorldIdtemDatabaseEditor : EditorWindow{
		bool fo = false;

		void OnGUI(){
			GUIStyle style = EditorStyles.foldoutPreDrop;
			//.....................*What now???*.....................//
			fo = EditorGUILayout.Foldout (fo, "Foldout", style);
		}
	}

thanks in advance for any suggestions.