[plt-scheme] scrollable table

I'm trying to make a scrollable table, where the rows and columns are
aligned, and scrollbars let you go down the rows, or across the columns,
either smoothly or in a quantized fashion. I saw (planet
williams/table-panel:1/table-panel)) but it doesn't have any scrollbars,
and you can't add a panel to a canvas, which seems to be the only thing
that has scrollbars.