1) Create a task, let's say 'aaa';
2) Create another task, let's say 'bbb';
3) Arrange tasks as task 'bbb' is above 'aaa' (default behaviour, I think);
4) For task 'bbb' check "Milestone";
5) For task 'aaa', modify work, let's say 3 days;
6) Make 'aaa' a subtask for 'bbb';
As you can probably check, the lenght of 'bbb' is 3 days, but the "Milestone"
remains checked (and grayed, so can't be unchecked) and the lenght in the gantt
chart is zero. Everything else is correct, dependent tasks start ok.
I would expect that, when adding a subtask, the "Milestone" become unchecked,
and the length (in the gantt chart) to be correct.
To correct the situation, I had to "unindent" all subtasks, uncheck "Milestone"
and "indent" again all the subtasks.