1. A method in a computing system for navigating an electronic document, comprising: electronically capturing a portion of a rendered document, the portion including a text fragment within the rendered document; in response to the capture, identifying (1) an electronic document contained in a corpus of electronic documents, the identified electronic document containing the captured document portion, and (2) a position within the identified electronic document at which the selected document portion occurs; accessing a markup layer that relates to the identified electronic document and determines custom actions to be made available in response to captures from particular positions in the identified electronic document; identifying actions associated with the identified position in the identified electronic document, wherein at least one of the identified actions was associated with the identified position in the identified electronic document before an occurrence of an electronic capture of the portion of the rendered document; and making the identified actions available to a user who captured the portion of the rendered document.