Snaps

F9 – Snap to first helper [Place architect exactly on first helper]

Shift+F9 - Snap to second helper [Place architect exactly on second helper]

Ctrl+F – Snap to perpendicular foot [Snap to foot of perpendicular dropped on segment formed by helpers]

Ctrl+J – Snap to corner or intersection [Snap to corner of any obj OR to intersect between 2 edges (one of which has the helpers)]

F4 – Shift helpers to previous edge

F3 – Shift helpers to next edge