Custom interactive JS
fig.save(..., extra_js=...)/fig.to_html(..., extra_js=...) inline a
caller-supplied JS string into the page – to add to plotpress’s own
toolbar (include_default_js left at its default True:
window.plotpressAddTool(...) registers a real button in its own row,
joining the same single-selection group as Axis Span/Axis Zoom/Point
Picking if given a mode), or to replace it entirely
(include_default_js=False drops
plotpress’s own JS – extra_js becomes the only interactivity this page
gets, built from the raw #plotpress-meta/#plotpress-pick JSON
payloads and #plotpress-svg directly). Nothing about either fetches
anything external on its own – extra_js is inlined the same as
plotpress’s own JS, same as every other interactive HTML plotpress writes.
