NGUI drag and drop snap

Hi everyone,

im using NGUI, specifically the drag and drop feature, i have figured out how to orientate in the right direction and place at the right height, but i cant figure out how to make it snap to a grid.

i have made a grid from multiple planes and im assuming its something really simple im not getting,

i dont have the code right now because im at work but its the NGUI drop script im assuming needs the edit, i will post a section of the code later.

in the mean time if anyone has any ideas or and examples of what they have done it would be a great help, im basically making a very basic sim/tycoon game, so its drag from GUI add to grid.

thanks guys.