A colgroup of percentages is the only state, so widths never touch the
cells: one <col> per column, table-layout fixed, and the browser does the
rest. A drag moves one seam and the pair either side trade width, so the
table box never changes size mid-drag — no reflow of the message around
it, no scrollbar appearing under the pointer.
Handles are markup inside each <th>; the table listens once and resolves
the grabbed seam from the DOM, so there is no context, no per-column
component, and no index threading. Tables stay in auto layout until they
are resized, and double-clicking a seam hands them back to it — the same
reset gesture the pane sashes use.
On a 43-row table a 40-step drag mutates 78 col[style] attributes and
touches no cell.
Brooklyn Nicholson
145cd763ca