Adding a Slack Bar Style to Other Gantt Chart Views
A useful addition to the Tracking Gantt or the view you build to monitor your critical path is a bar that represents the slack for each task. This bar is drawn from the finish date of a task to the measure called Total Slack.
Adding a Slack Bar
Display the view of your choice. In this example, we will be editing the Tracking Gantt view.
Click Format, Bar Styles to display the Bar Styles dialog.
Highlight the row just below the Task bar.
Click the Insert Row button.
In the Name field, enter Slack.
In the Show For Tasks field, enter Normal, Noncritical.
In the From field, select Finish.
In the To field, select Total Slack.
In the Shape field, select the last shape, which is a thin line drawn at the bottom of the row.
Select the desired pattern and color .
Click OK.
The new Slack bar is drawn for noncritical tasks, and is drawn from the finish of the task to the date to which it could slip and not affect the project finish date.
Display the view of your choice. In this example, we will be editing the Tracking Gantt view. 
Click Format, Bar Styles to display the Bar Styles dialog. 
Highlight the row just below the Task bar. 
Click the Insert Row button. 
In the Name field, enter Slack. 
In the Show For Tasks field, enter Normal, Noncritical. 
In the From field, select Finish. 
In the To field, select Total Slack. 
In the Shape field, select the last shape, which is a thin line drawn at the bottom of the row. 
Select the desired pattern and color . 
Click OK. 
The new Slack bar is drawn for noncritical tasks, and is drawn from the finish of the task to the date to which it could slip and not affect the project finish date. 
