Firstly, if the grid is on, then clicking on a piece to select it makes it jump to the grid. This is bad because the user may want to select the piece to make copies of it without changing its current position; and if they
do want to adjust it to the grid they have the option of dragging it a short way and then back to its original position.
Secondly, again only if the grid is on, clicking on a piece with a negative X- or Y-coordinate, even if it
is aligned with the grid, makes it jump by one grid-tile. This part is definitely a bug