A free comprehensive guide for evaluating site structures
To test visual design (page layout, color, graphics, and so on), we typically use tools that test an actual working site with production graphics or tools that test a screenshot of a given page (often mocked up in something like Photoshop).
If we want to find out if a particular placement of a control (or its size or shape or color) is effective or not, we can use the first-click tools described in Testing navigation.
If we're interested in testing more complex interactions (up to and including actual use of the working site), then we can use the "full-on" usability testing tools described in Testing overall usability.
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