An Introduction to Designing User Interface Controls at SAP (SAP Design Guild) -- "Around the office at the Product Design Center here at SAP's development headquarters in Walldorf, Germany, our work centers mainly around user interface controls, or just "controls" for short. We spend our days specifying controls, designing controls, prototyping controls, developing controls and testing controls. But what is a control? Are there different categories of controls? How does a control come into being?"