Evaluating direct manipulation operations for constraint-based layout

Abstract. Layout managers are used to control the placement of widgets in graphical user interfaces (GUIs). Constraint-based layout managers are more powerful than other ones. However, they are also more complex and their lay-outs are prone to problems that usually require direct editing of constraints. To-day, designers commonly use GUI builders to specify GUIs. The complexities of traditional approaches to constraint-based layouts pose challenges for GUI builders. We evaluate a novel GUI builder, the Auckland Layout Editor (ALE), which addresses these challenges by enabling GUI designers to specify constraint-based layouts via direct manipulation using simple, mouse-based operations. These operations hide the complexity of the constraint-based layout model, while giving designers access to its benefits. In a user evaluation we compared ALE with two other mainstream layout builders, a grid-based and a constraint-based one. The time taken to create real-istic sample layouts with our builder was significantly shorter, and most partici-pants preferred ALE’s approach. The evaluation demonstrates that good usabil-ity for authoring constraint-based layouts is possible