While dragging an element:
Snap to grid is a feature which allows you to drag an element in precise steps—useful for exact positioning.
To enable snap to grid, select an element and click one or both of the snap to grid buttons, located to the right of the horizontal and vertical offset fields in the Inspector. You can then drag the element in steps equal to the grid spacing. The default value is 0.5 sp.
To change the grid spacing: