nsIFilePicker
to create an instance, use: var filepicker = components.classes["@mozilla.org/filepicker;1"] .createinstance(components.interfaces.nsifilepicker); method overview void appendfilter(in astring title, in astring filter); void appendfilters(in long filtermask); void init(in nsidomwindow parent, in astring title, in short mode); void open(in nsifilepickershowncallback afilepickershowncallback); short show(); obsolete since gecko 57.0 attributes attribute type description addtorecentdocs boolean if true, the file is added to the operating system's "recent documents" list (if the operating system has one; nothing happens if there is no such concept on the user's platform).
... void open( in nsifilepickershowncallback afilepickershowncallback ); parameters afilepickershowncallback the nsifilepickershowncallback to be called on completion.