Certain factors are considered when the task order is determined in the ToDo sidebar. Considerations include, due date, whether a task was recently worked on, how many estimated hours are remaining and start dates. Calculations are used to assign each task a score which determines the order they appear.
The order tasks appear in the ToDo sidebar from top to bottom are:
Overdue tasks - any incomplete tasks assigned to the user that are past their due date.
Tasks that have been recently worked on (regardless of start and due dates). 'Recently worked on' encapsulates any tasks that have had time tracked on them in the period starting from the previous Monday through to this Friday.
In progress tasks based on the ratio of work remaining vs time until deadline (a task with 20hrs remaining that is due tomorrow will be higher on the list).
Tasks that have had time recorded on them but have no end date set.
Tasks that are due to start in the future.