Expand all option to expand quickly all the nested subtasks in Timeline view

Provide an "Expand all" command to expand all the nested tasks with one click, in the "Timeline" view.
There's a big waste of time in reopening all the nested tasks every time you come back to those screens, since the view is reset.
Another way to solve this would be to let the project to remember what tasks have been expanded and the same view will be proposed the next time the section is opened.