Timeline Slicer is missing data

We have issue with the Timeline Slicer only accepting a single Date field "Time".  Because all of the time base data we work with (events, calendar data, appointments, etc) contain a start/end or start and duration. 

This makes the timeline slicer suffer because it can miss data when it is filtering.  For instance, we chose start date for the Time field, the Timeline slicer will correctly include events where the start date falls within the slicer range, but leave out events where the start happens before the slicer range and the end falls after the slicer start.  This can be mis leading to the user, because they expect an overlapping event like this to be included.  So user confidence is lost on the Timeline Slicer.

Is there a hidden feature that will allow the Timeline Slicer filter based on a start and end?  This would make the visual a very powerful report filter.

Suggestion 1:

The developers can attain this functionality and be backwards compatible by adding an optional end time field and when a data field is included, add the logic to detect where events with start/end overlap the timeslicer start end.  This answer to this post shows how simple overlapping period detection is. 

Suggestion 2:

Is the Timeline Visual open source?  We would gladly try and make this change if so.  

Workaround attempted:

We tried to use two slicers on our reports (one to take the start and one to take the end) - but these when they are not automatically synched is too cumbersome on the user.  Also the visual is too large and having 2 on the report takes too much report real estate.  So the work around was abandoned

Is there something I am missing to get the slicer to detect date range overlaps?

Thanks.