The main component of the file browser dialogue consists of two scroll lists placed side by side. The left list is labelled "Directory" and shows a list of other directories to choose from. The right list is the list of files in the currently displayed directory.
Double clicking with the left mouse button on a directory updates the file list. If a filter file browser component is visible then the current directory will be displayed as the start of the filter. The directory named ".." is the parent directory of the current directory.
Single clicking on a file name updates the Selection component. Double clicking on a file name chooses this file and removes the dialogue. That is, it is equivalent to single clicking on the file to update the selection followed by pressing the `OK' button.
When the dialogue allows multiple files to be selected (then titled "Open multiple files") holding down the Ctrl key will retain items already chosen.