selection highlight

I’m testing blender at the moment and i like the modelling tools and general workflow a lot. But I’m missing some selection tools. I’m used to model in Silo3d, which has an awesome selection highlight feature. The good thing is that your mousecoursor doesn’t need to be positioned over a vertex or over an edge to select it. The closest element from the mouse cursor position is selected despite its distance. Is it possible to integrate something like that into blender with scripting? It is also important that it is not a separate tool like the circle select tool. I want to use it instead of the rectangle selection.

here is a little gif which shows that feature.

I believe that you need to do raycasting which gets mouse screen position and also get the component underneath it and changes its color.

I would like more info on this implementation in a non-BGE environment as well.