Enhancement: Add toggle option to switch between column or row-first order placement of entries in task list

When using a multi row panel, window entries in the task list are currently first ordered vertically by column, before making use of the horizontal space. I would like to be able to change it so that they will instead order first in the horizontal direction. That is, they would populate the first row, and only after filling that would they then start to spill over to the second row.

Forum thread: https://forum.xfce.org/viewtopic.php?id=16592

Thank you for your attention!