SubEthaEdit 1.1 and higher supports following interfaces to serve as an external editor for other applications.
Project Builder and Xcode support external editors. SubEthaEdit implements a subset of the Metrowerks CodeWarrior IDE interface for external editors to integrate with Project Builder/Xcode.
SubEthaEdit's integration includes following features: Double-clicking in any PB list will open the file in SubEthaEdit, and if there's a selection range or line number, SubEthaEdit will show it. (e.g. for build results, find results, bookmarks, etc...). If you start a build with unsaved files, Project Builder will include unsaved SubEthaEdit files in the Save All dialog, and allow you to save them.
SubEthaEdit supports the ODB Editor Suite (also known as The External Editor Protocol) to act as an external editor for applications implementing this suite.
Many FTP clients implement this interface, for example Transmit, Fetch and NetFinder. These applications have an "Edit with <Editor>" menu command. When you select a file in a remote directory and choose that command, the file is downloaded to a temporary location and opened in the external editor. When the user saves the document from the external editor, the file is automatically uploaded back to the remote machine by the FTP client.