Updated UI.Container to allow you to drag and drop into the first slot (always empty). Github
You will also need the image (On the github link or make your own).

-    for i = 1, itemsToShow do 
+    for i = 0, itemsToShow do
      local widget = g_ui.createWidget("BotItem", widget.items)
+      if i == 0 then
+        widget:setImageSource("/images/ui/item-blessed")
+      end