[Tom Bunch]

They are probably ghosts of tasks gone by. Each chunk of a split task has a little object responsible for drawing it, and you've probably found a way to make a split chunk go away such that we're not doing proper cleanup.

Yep, indeed, if leveling splits a task, undo leveling will leave those old cells around. It looks like it can even unassign the unsplit task.

Thanks for the report, and sorry for the inconvenience. We'll have a look at that soon.

-Tom