Once the user has identified a document of interest, navigation becomes a
task of finding the appropriate location within a document. This may be a
matter of searching for the occurrence of a string or of finding some
structural component. Landmark tools are designed to allow the user to
survey some aspect of the overall document. The Landmark tools are
intended for use when when the entire document is not visible in the display
window. The tools are dependent upon the availability of a scroll bar with
a variable sized thumb. In CASCADE, thumb size is determined on a line
basis.
The mural allows the user to quickly locate potential areas of
interest in the document and the thumb is used to quickly navigate to that
point. Two Landmark tools are currently employed in
CASCADE --Mural and Tilebars.