!Stroke Shapes add a hand-painted quality to a selected path. The funny black things on the left are the stroke shapes which have been applied to the line on the right.
I suspect there will be more than the five Stroke Shapes shown here when Xara finally ships. (Say that ten times quickly!)
To apply a Stroke Shape to a path, select the path, select the desired Stroke Shape
and point size form the Line Gallery, and press Apply. These are dynamic shapes, which means that they can be altered at any time.