Editing Z-order (section)

{{About|the graphical user interface concept|the space-filling curve|Z-order curve}}
{{more citations needed|date=May 2007}}

'''Z-order''' is an ordering of overlapping two-dimensional objects, such as [[Window (computing)|windows]] in a [[stacking window manager]], shapes in a [[vector graphics editor]], or objects in a 3D application.<ref name="CGGraphics">Foley, James, Andries van Dam, Steven Feiner, and John Hughes (1987). ''[[Computer Graphics: Principles and Practice]]''. Reading, Massachusetts: Addison-Wesley Publishing Company. pp. 870-871.</ref> One of the features of a typical GUI is that windows may overlap, so that one window hides part or all of another. When two windows overlap, their Z-order determines which one appears on top of the other.