Whether a file chooser not in %GTK_FILE_CHOOSER_ACTION_OPEN mode
will offer the user to create new folders.
Optional do_overwrite_confirmation
do_overwrite_confirmation?:boolean
Whether a file chooser in %GTK_FILE_CHOOSER_ACTION_SAVE mode
will present an overwrite confirmation dialog if the user
selects a file name that already exists.
Whether a file chooser not in %GTK_FILE_CHOOSER_ACTION_OPEN mode will offer the user to create new folders.