Edge points: click in grid = new point · drag = move freely · double-click = delete · hover shows coordinates (from cast-on and from center).
Arcs: drag the brown midpoint of a segment sideways = bulge it into an arc (armhole); points on the axis shape the neckline and hem · double-click flattens.
Marks: + increase stitches · − decrease stitches · ⊟ bind off at once (steep section). Knitting goes bottom (cast-on) up; in symmetric mode the left (grey) half mirrors.