It would be nice to be able to lock the time of certain
tasks (particularly milestones), so that when dragging
predecessors around, the predecessor is constrained by
the locked-in milestone, instead of just moving the
milestone if it needs to.
Having set the duration of a task, move it forwards or
backwards in time by shift-clicking on the middle of the
task bar and drag forwards or backwards.
And finally, when copying and pasting a task with sub-
tasks, keep the relationships in the pasted sub-tasks.