F4: Edit
Place the cursor bar (small rectangle) over the file you want to edit and press F4. This starts the editor you selected in the configuration dialog, and loads the selected file. As a default, Windows notepad will start. It is limited to text files of limited size. If you want to edit files of different types, just double click on the file or press ENTER. The program associated with the file will then be started. You can associate data file extensions with programs using Files - Associate with.
If the source directory shows the contents of an archive, the file under the cursor is unpacked to a temporary file and loaded into the (previously) selected editor. If you change the file and then close the editor, Total Commander will ask you if you want to repack the file into the archive. If you choose yes, the archive will be updated and the temporary file erased. If you choose no, the temporary file is erased and the archive is left unchanged.
If you use a multiple-document editor and it was already running when you pressed F4 within an archive, then Total Commander will not be informed when the editor closes. Therefore Total Commander will show a little dialog box with the name of the edited file, in which you can confirm when you are done with that file. After clicking on Close, Total Commander will proceed as described above.