Plan on Picking

After some testing and thinking, I think I will try to simplest way: rendering grid and use them for mouse picking. A side benefits of this design is I can also have a very simple implementation for multi-level selections. The user will select different height, and I will just draw and pick grids at that height. It's simple and clear.
The disadvantage of this is I can't use the mouse to cycle through different faces of a tile by letting the user click on the face. I think I might be able to add another window maybe that let the user select it using drop down or scroll bar (ideally).
But first thing first, I will have to get the simple stuff done before I get to the finer details.