When you are dragging a selection box/circle or dragging out a shape, it'd be splendid if holding down the spacebar would move the selection/object.
This makes it easy to get an exact selection... or enables you to size and position in one simple move saving a lot of futzing and keeping you in flow.
This interaction can be found while taking a native screenshot on your mac (shift+cmd+4+drag... + hold spacebar) or on all the other drawing apps made by the company named after dirt bricks.... and Affinity is better than dirt bricks' products.