Move left
Click to move the selected tasks to the left within the bar chart, ie to an earlier date. The selected tasks move left by one of the current snapping time units each time you click the control. For example, if the current snapping time unit is weeks, the selected tasks move a week earlier.
If you have selected a progress period line on the bar chart, you can use this control to move the report date of the progress period to the left, ie to an earlier date. The report date moves left by one of the current snapping time units each time you click the control.