Here you can set file save/open windows height and width in per cents, and turn off Show the full path in the window caption if you want to see just file name in the caption.
Show the common close button - show or hide the shared close button (similar to the close button in Firefox) that closes the current document.
Exclusive "Enter" mode at save/open dialogs - when this mode is activated, the "Enter" key at save/open dialogs acts like the default confirmation even if the OK button is not focused. I.e. in that mode you can press Enter when you type the file name at the file name entry, and the Enter will be accepted as the OK. Such mode has the side effect - you cannot use Enter to navigate through directories and files at the files panel or bookmarks panel. So turn it ON if you use mouse for those operations and if you like to press Enter to confirm the entered filename (instead of clicking the OK button).