Current functionality is limited to when you click to select an item from your toolbar (or similar).
I find I naturally left click to place, right click to delete. What ends up happening is that I inevitably end up with like 3 belts in my inventory. Then when I place belts, I get 3, then my cursor is empty, and I have to click belts again, to continue placing belt ghosts. Also, when I need to smart replace with an underground belt, but I have 1 in my inventory, it fails to place any, gives a warning, then causes belts to mix that shouldn't be mixing. Happens ALL THE TIME... getting frustrated.