XS report contains the XS breakout by metric and items with XS.
The breakout by metric shows you a Pie chart of the sources of XS (according to the current XS configuration) within the item currently selected in the drilldown.
The items with XS list shows you the individual violations. Clicking on a slice of the pie will filter the list for the selected problem. To deselect a problem, click it again in the pie chart - the list will become un-filtered.
Double-clicking on an item in the items with XS list will take you to that item's child graph in the composition perspective (unless the item is a method, in which case the source viewer will pop up).