This extends the standard selection painting to also highlight
the editable text labels and their placement strategies should
there be only one selected item.
Construct a new path to coordinate conversion object which positions at a
percentage along a path with a given distance perpendicular to the path
at the anchor point.
Construct a new path to coordinate conversion object which positions
an anchor point on the path at a percentage along a path with an offset,
and from the anchor point at a distance measured at a given angle.
Construct a new path to coordinate conversion object which positions
an anchor point on the path at a percentage along a path with an offset,
and from the anchor point at a distance measured in X, Y coordinates.
Deprecated.in 0.29.1 This is only a helper class for save/load and will
become package scope. It is not designed for reuse outside this package.
TODO: Bob says: I don't like the naming of this class. Its confusing that
its called ...Window and yet it is not a window. Lets rename once we have
it hidden.