The top of the window consists of 2 buttons with which you can change the current directory. The first button displays the current directory name. Clicking on the button brings up a popup menu showing the entire directory hierarchy with the current directory at the bottom. Select one of the other directories to jump to that position in the hierarchy.
The next button, showing a folder icon with an arrow, will move you up one directory level.
The file listing shows the names of all files which have the form specified in "File of type" field, their file sizes, and last modification dates. When the "List Fits files only" is selected, only FITS files are shown as well as all the compressed files. Double click a file name to open that file. Directories are listed with "/" (":" on MacOS). Double click a directory name to move to that directory.
In the "File Name" field, the currently selected file name is shown. One can type a partial filename and press TAB to invoke automatic filename completion. One can also type a directory path to move quickly to another location without having to navigate all the intervening directories.
The file list will be filtered using the wildcard string contained in this entry field.
Click this button to insert the currently selected file name corresponding entry in the par file editing windows.