The multiplicity of windows and the heterogeneity of their contents mean that the user is repeatedly brought back into contact with the interface. The user can oscillate between manipulating the windows and examining their contents. Icons, menus, toolbars add further layers of visual and verbal meaning
The windowed computer surface is simultaneously automatic (the interface consists of layers of programming that are executed with each click of the mouse) and interactive (these layers of programming always return control to the user who then initiates another automated action).
The different mediums can e.g. be replaced, juxtapostes, or absorbed by each other.