Reordering sub-tasks from an issue's detailed view is a very hard process because each time you click on an arrow to move a task up or down, a full postback occurs.

Would it be possible to move tasks around using drag and drop in an "AJAX" manner (like everywhere else in JIRA) to avoid tasks full page reload?

This is problem because sub-tasks moved around in the Kanban Board view do not seem to affect the sub-tasks orders in the issue's detailed view.