Sort Gantt widget (grouped by boards) by "Left pane board position"

We have a dashboard with a Gantt widget that shows a rollup of all items in a board and is grouped by boards. I would like to sort boards order by “Left pane board position” but this is not an option for Gantt widgets; instead, it displays the board order in the order they were created, even if you deselect the boards and re-select them in the desired order. It is an option to sort by left pane board position for Table widgets however.