If there is an object whose size is bigger than the size of a grid's cell (e.g instance size is 32, and cell's size is 16) :
If you select it with the mouse with a position which is not near the left top corner of the object, at first it will be shifted :
This means it looks a little bit jerky when you start to move the object. I propose to remove this effect (the same as GM Studio). If you select the object in the middle, for instance, the mouse cursor will stay in the middle of the object.