Master/detail

100,000 orders. Click ▸ (or press Enter on a row) and the items of the order appear right below it – as a second GuiExpert table over the full width, also over the fixed order column. Scroll far away and back: the detail is still there with its own scroll position and selection, it was only hidden. The detail can be anything: a nested table, a form, a chart, a React/Vue/Svelte/Angular component. MIT-licensed, no dependencies.

const tableOptions = {
  ...new TableOptions(),
  masterDetail: {
    detailHeight: 220,                       // px – or "auto" (measured)
    detailRenderer: (container, order, ctx) => {
      ctx.createTable({                      // destroyed together with the detail row
        tableModel: TableFactory.createTableModel({ rows: order.items, properties: ["sku", "product", "quantity"] })
      });
    }
  }
};
tableApi.setDetailExpanded(order, true);     // or a click on ▸, or Enter

Millions of rows: details are created when they scroll into view and hidden (not destroyed) when they leave it; row positions use prefix sums, so scrolling stays fast with many open details.
Sorting and filtering keep each detail with its order.
Events stay inside: clicks and arrow keys in the item table do not move the focus of the order table.
Keyboard and screen readers: Enter toggles, Tab moves into the open detail, Shift+Tab back; aria-expanded.
Remembered: the open orders are part of the table state (autoRestoreDetailState).

Docs: instructions.md 6.18 · API: TableApi.setDetailExpanded, MasterDetailOptionsIf.