Const
How much of a pane (or the whole chart) must be repainted this frame.
Readonly
Repaint only the top (overlay) canvas: the crosshair and the top-layer primitives.
Recompute scales/ticks then repaint everything.
Repaint the base canvas at the current scales: series moved or changed, no rescale.
Nothing to do.
How much of a pane (or the whole chart) must be repainted this frame.