The Folding>Narrow to Fold command hides all lines except those in the fold containing the caret. When editing a file with folding, this can be used to "focus" in on a block of code and create a less cluttered display. To display the entire buffer again, invoke the Folding>Expand All Folds command.

Folding>Narrow to Selection works in a similar manner, except it hides all lines except those in the selection, rather than those in the current fold.