I answer this and also the other post FR : Flow grid & engraving fix - #11 by AMazedBrane
You can move/reposition the flows also vertically in Project Infos!. You can also select multiple flows,also not contiguous, and move them together , with the arrows in the lower part of the window. If you selected multiple non contiguous flows, they will become contiguous after moving 
so there is much flexibility.
I think a grid would make unclear what comes first and what comes after.
