I think we need to agree to the same definitions of tasks and events, in order to avoid misunderstanding:
An event/meeting is an appointment that is taking place at a certain time at a certain day. It has a duration and it involves other people, hence the term “meeting”.
An all day lasting event is something like a course of instruction, or a funfair, or a journey.
A task, on the other hand, is something that has to be done, like changing the car’s tyres, feeding the cat, or chopping wood. A task can necessitate to be done at a certain time, and it can involve other people, but usually it is something that just has to be done by oneself, and usually it does not require to be done at an exact moment in time.
An “all day” task is not a task that lasts a hole day, but a task that can be done at any time during that day, no matter if it’s done at 8am or at 5pm. When it’s done, it’s done, but it does not really last the hole day, like changing the tyres. (Of course, a task can last the hole day, if one works too slow. )
There are even tasks that are not bound to any specific day at all, tasks that can be done at any time in the future, like for example “get famous”. And, of course, there are tasks that have to be finished within a certain period of time, that do need a starting time and an ending time, and once the ending time has past, there’s no way of finishing that task any more.
That’s the way I look at it.
The problem with Lightning is, that it does not provide a way to make a task “all day”. This option is only available when creating events in Lightning. Other calender applications, including NC, do provide a button/option to make a task “all day”, and then those tasks are shown as “all day” in other calender apps as well. If I create a task the way you do it, Lightning does not show a “due” date at all. If I set an ending date without a starting date, Lightning and other calender apps list that task as due on day x at 00:00 o’clock.
And that’s quite annoying, because 1 minute after midnight that task is marked as overdue, while originally that task was meant to be done at any time that day. And that’s what I’d like to change: I do not want to see overdue tasks (eg on my Android calender), while there are still 23 hours left to execute those tasks. Since Mozilla are not really interested in solving this bug, that has been existing for several years now, I think there are two possible ways of dealing with this problem: abandon Thunderbird and Lightning completely from my desktop machine, or I can try to make NC set the “all day” option automatically on every task.