Class ComparisonController

Put an instrument on the chart alongside the primary series.

Take them all off, putting every pane back the way it was found.

Remove every comparison and forget the chart.

Every comparison on the chart, in the order they were added.

Re-project every instrument onto the primary's current bars. Called for free when the shared time axis changes (see sync); a host only needs it after replacing the primary's data with a different set of the same length, which the length check cannot see.

Take one instrument off. Returns false if it was already gone.

Change the mode the panes are held in while comparisons are on them. Panes that already have one switch immediately.

Bring the overlay scales in line with the primary axis, re-aligning first if the shared time axis has moved under us (a live bar, history paged in, a replay step). Runs once per base paint through the per-pane hook.

Re-aligning here writes series data mid-frame, which is safe because the hook is a bottom primitive: it runs after the pane has autoscaled and before any series is drawn, so the frame that notices the change is also the frame that draws it. The repaint that write asks for lands on the next frame, or re-enters this one on a host that runs frames synchronously, which is what realign's guard is for.