Maximise the window, or return to the previous window display size; return to the old screen setting (CTRL-UPARROW).
Delete the ".Bpib" help file in the current directory. A new ".Bpib" is only created once the directory is read again.
Indicates whether the lower part, where information about the active picture is displayed, is shown.
In parts of the Blender interface where pictures can be loaded, you generally have the option of using a FileSelect window or the ImageSelect window. For the most part, the functionality is the same. The ImageSelect window reads the directory and examines each file to see if it is a recognisable image. After the entire directory is scanned, the images are loaded and displayed as a thumbnail and saved in the ".Bpib" file. If a ".Bpib" file already exists, it is first read in and compared to the contents of the directory.
The file $HOME/.Bfs contains a number of pre-sets that are shown in this menu. While a file is being read or written, the directory involved is temporarily added to the menu.