http://en.wikipedia.org/wiki/Zooming_user_interfaceIn computing, a zooming user interface or zoomable user interface (ZUI, pronounced zoo-ee) is a graphical environment where users can change the scale of the viewed area in order to see more detail or less. A ZUI is a type of graphical user interface (GUI). Information elements appear directly on an infinite virtual desktop (usually created using vector graphics), instead of in windows. Users can pan across the virtual surface in two dimensions and zoom into objects of interest. For example, as you zoom into a text object it may be represented as a small dot, then a thumbnail of a page of text, then a full-sized page and finally a magnified view of the page....
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Projects
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BlueBottle/Aos Bluebottle OS is an evolution of Native Oberon and has a zooming user interface.
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Well, we don't have vector graphics exactly, but zoom in on the new window titlebar icons to see that it isn't just bitmaps either.