The way I select objects after they've been placed on the map is: I click on the t for tile, then the o for objects, then I click or right click on the object on the map. I can then edit the object if it has editable properties. I can also move the object that way.
To delete the object, I click on the sissors at the top of the editor.
I also click the t and o to clear the last object selected.
I hope this helps some people that are having troubles editing and/or selecting placed objects.