this shows the data date line. People find it hard to distinguish. If you could make it thicker please.
A possible future improvement is to add a sliding scale to allow the data date and focus time markers to be resized to the desired thickness.
In the meantime, If you're having a hard time distinguishing the Data Date marker from the Links in the Gantt chart, you can change the color of one or both in Options>Gantt Chart>Colours>Links/ Data Date Marker.