For example the HandleMouseMove event can not be overridden in order to allow dragging on the Y coordinate. Also some internal methods should be exposed.
To reproduce: Add Tasks which appear far after the start of the timeline. You will notice that some of them are not displayed at the right position.
Open QSF, go to GanttView, open the First Look demo, click a date time cell in, click anywhere else, exception occurs.
Add new timeline view which shows Time/Hours