GetFile(cmd = "Open", file = NULL, exts = NULL, initialdir = NULL,
initialfile = NULL, defaultextension = NULL,
win.title = cmd, multi = FALSE, parent = NULL)"Open" or "Save As" file
management pop up dialog box is implemented.file can be a readable text-mode
connection.TRUE multiple files may be selected;
its default is FALSE.multi is FALSE returns a list containing the following
components:file pathfilefile namefile extensionfile type