Most functions are inherited from the labelled drawing editor. There is an outline drawn of unit size centered on (0,0) which indicates the highlighted region of the drawing when used in the lab. In general, drawings should fill but not extend beyond this box. The size at which the component is finally drawn can be set with the expansionFactor fariable in the drawing.
The various components of a drawing are always draw in the order in which they are created, so it is important to create any opaque background components before the detail on top of them or the latter will be obscured.