think-cell technical report TC2003/01 A GUI-based Interaction ...

4.3 Specifying the User Interface INTERACTION CONCEPT
Late-breaking result: In recent user studies with the prototype, it turned out
that users very much rely on the body of a shape being responsive for selection.
Users had great difficulties to understand and use the outline-based selection, and
no advantage for the outline-based approach could be observed. Therefore, in up-
coming prototypes selection will be implemented to behave exactly like in ordinary
PowerPoint.
Nearest Neighbor Selection
A common problem of the PowerPoint way to select shapes arises when a shape is
hidden behind some other shape. A shape that is not visible on the slide cannot be
selected by a single click. Experienced PowerPoint users choose the lasso to catch
such a hidden shape.
I propose another solution, which is based on features and their outlines. Based
on a strictly 2-dimensional nearest neighbor algorithm, the feature outlines always
highlight, even when the associated shape is hidden underneath some other objects.
This is illustrated by figure 30: Feature selection always works the same, regardless
of the smart element’s visibility. Since the bounding box of a smart element is also
a feature with a responsive outline, my approach can track down smart elements
that are hidden in the background of a slide simply by mouse-over.
(a) Outlines of hidden elements highlight on
mouse-over.
(b) Selection and multiple selection works regardless
of the visibility of the shapes.
Figure 30: A strictly 2-dimensional nearest neighbor approach allows the selection
of shapes in the background.
4.3.4 Adjusting the Smart Grid
In sections 4.3.1 and 4.3.2 I explained a range of means that help the user to build
a desired layout by implicitly specifying alignment relations when new elements are
added. Still, the need will arise to modify the alignment of elements after they are
already placed into the smart grid. My concept provides two ways to adjust the
smart grid and its contained elements: The user may manually move gridlines and
the user may displace the elements’ anchorpoints, binding them to new or existing
gridlines as desired.
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