Update the pane's filter when updating the start date of a task

[SqAtx]

Fixes #1039

Updating the start date of a task may influence whether or not it needs to be visible. For example, if you're on the Actionable pane and you set the start date of a task to some time in the future, then the task is no longer actionable and needs to disappear from that view.

Testing by having some tasks in the Actionable pane, then verifying that the following make the task disappear from the pane:

• click on a task and then on Start Tomorrow
• right-click on a task > Set Start Date > "anything in the future"
• double-click on a task > modify "Starts on" to a date in the future > close task editor
• create a new task > without closing the editor, add a child to it > click on child > click on Open Parent

[SqAtx]

Note that we're again running into the fact that the same functionality (updating the start date of a task) is implemented in two different methods (update_start_date() and update_start_to_next_day()).

I'd like to have one call the other instead, but that's not really related to the current change so I didn't include it here.

[diegogangl]

Looks good, except for a couple nitpicks and it works. Thanks! There's one part missing though, if the start date is changed in the task editor using the calendar widget. Maybe we should call refresh() when the window is destoryed?

[SqAtx]

There's one part missing though, if the start date is changed in the task editor using the calendar widget. Maybe we should call refresh() when the window is destoryed?

Good point! I actually noticed that earlier this week too, but didn't have time to look into it further. Will do.

[SqAtx]

I also added a .refresh() to TaskEditor.destruction(). I was originally wondering if I shouldn't add it to Application.close_task(), whose docstring is "Close a task editor window."

But destruction() is linked to the "close-request" callback of the editor, so I think it makes most sense there.

[diegogangl]

Looks good now 👍
Merging