The options on this page let you control what Opus does when you double-click on certain types of files in a file display. The File Types system gives you far more control over double-click actions than this page.


You can make Opus use its internal image viewer to view pictures on double-click, even if the file's normal filetype action is to open a different app. You can choose to have this happen for all recognized image files, or only unregistered file types.


If Use internal sound player for WAV files is turned on and you double-click on a .wav file, Opus will play the file in its own simple sound player rather than opening the normal media player application.

Unknown file types

If the Open unregistered file types in text viewer if they appear to be plain text option is on, and you double-click on a file of an unregistered type (or one without a file extension), Opus will examine its contents, and if it looks like a plain text file it will treat it as one, and open it in the default text viewer (usually Notepad).

This is particularly handy for files from other file systems that don't necessarily have a .txt extension. If you want to use a text viewer other than the default you can select one to use on the External Tools page.