A footer that aggregates each column over the visible rows.
Numeric columns start on sum; click the little aggregate button to
cycle sum → avg → min → max → count. Apply a filter and the footer recomputes;
your per-column choices persist across reloads. The footer is injected as a
<tfoot> and removes byte-identically when toggled off.
Try it
The footer shows each numeric column's sum and each text column's count
over the visible rows.
Click an aggregate button (e.g. on Units) to cycle through
sum / avg / min / max / count — your choice is saved per page.
Click GS, filter Units with the ▽ lozenge, and
watch the footer recompute over just the matching rows.
Untick Summary row in the panel to remove the footer, then re-tick
it — it comes back with your saved aggregate choices, no reload.