The FileBrowserWindow plugin offers a convenient way to access your (physical) files, remembering the folder or file that was selected when you last ran OpenCOR. By default, your home directory is selected:
To double click on a folder expands its contents, as can be seen by double clicking on the
Similarly, to double click on a file results in that file being opened in OpenCOR. Its rendering depends on its type, if it is recognised, or on the view being currently selected.