Double clicking on a file name listed in the main PowerArchiver window will perform the same action that is performed when you double click on a file in My Computer or Windows Explorer. If the file is an executable (with a file extension of EXE, COM, BAT, or PIF), PowerArchiver will run it. Otherwise, PowerArchiver will open the file with the appropriate application. For example, files with the extension of .TXT are opened using Windows Notepad (unless you have changed the TXT association). The appropriate application is determined via Windows' file associations.
If you change the file while it is open, PowerArchiver will ask if you want to update the archive with the changed version of the file.