Enable "select instance on scene" in the external layout

Would like to be able to use the “select instance on scene” (right click on the object list) when in the external layout tab just like in the normal scene editor, I have lots of object and some of them are on top each other. I decided to not use too much layer and only modify the Z order instead.

With the feature that I request it will be easier to move and interact with objects that is stacked on top of each other easier, also I will know how many instance that is exist in the external layout.