Just that - a drawing with labels. Not much use on its own. The only subclass so far is the MeshedDrawingEditor which also constructs a triangular mesh on the regions defined in the drawing ready for use in ReactionDiffusion calculations.
Drawing elements can be torn off the templates at the top and dragged onto the diagram. To move or rescale an element, click on any point so it turns green, and then drag the center or any of the corners to change its shape or size. To add points, click the orange "proto-points" on the sides which then become real points that can be moved with the mouse. To move a point or whole component, drag it off the diagram.
There are two marker types at the top right, a rounded one for regions and an angular one for lines. The latter will stick to a point on a line, and will give its CcmbColor to the line. The region marker does not stick to the points, but should have its free node positioned anywhere in the region it is marking. Applications which define properties to be associated with lines or regions do so through these markers.