the second is a data grid with a tree view column that automatically calculates rollups and has advanced keyboard navigation and the ability to expand/collapse section.

emh.io/gpt/treeshee...

today i built two such prototypes that i think are worth sharing.

the first is an infinite canvas the user can add boxes to, connect those boxes, drag them around, zoom in and out, etc.

emh.io/gpt/canvas.h...

(dblclick to add, ctrl-click to connect, click and drag to move, mousewheel to zoom)