is it possible to change the timeline using a counter of days/months/years instead of precise dates? for example my customers need to set zero at the beginning of the graph (start of their activities) then put bars x days/months/years from the beginning (this activity starts 5 days from the beginning of the plan, and is long 2 weeks, or this activity is to be done every month for one day each, etc).

Answer

You can simple a pick a start time (maybe a non leap-year) and keep this as your zero-point. Then you add your zero point to all time values when you show them (this can be done once and for all by implementing the OnBeforeDSToTimeItem event and the OnBeforeTimeItemToDS event if you are data-bound).

Then you want to implement the OnDateScalerDrawString event to change the textual output of the date scale markers to something less specific, like maybe "Month 1" instead of "January".

You also need to implement the OnViewDateInformation to override the default span info presentation (this is the text normally found in the upper left corner)