Dragging an event within a Timeline view changes the $StartDate to the reflect the date indicated by the new; if $EndDate was also set, that too will update, i.e. the whole duration will move. From v5.8.0, this effect applies to selections of notes as well as individual notes.
Notes can be dragged from/to the "NO DATE" sidebar. Dragging onto the main timeline sets both $StartDate and $EndDate to the same data/time; dragging to the sidebar sets both to 'never'. However, be aware that the "NO DATE" sidebar is only shown if there are any descendant notes with no $StartDate value.
Notes can be dragged from - but not to - the "OUT OF RANGE" sidebar. Dragging onto the main timeline sets both $StartDate and $EndDate to the same data/time.
Event drags are undo-able, from v5.8.0.
Dragging note(s) between existing timeline bands will move the note(s) into that band. Holding the Shift key down during a vertical drag will ensure dates are not changed.
Dragging note(s) below the bottom existing timeline band will move the note(s) into that band.