off topic question

[Jeffrey Goddard <moosewood mooseroot org>]

ok, i realize this is probably off topic, but can someone explain what the
compiler is trying to tell me about these statements?

callbacks.c:27: warning: assignment discards qualifiers from pointer target type

   gchar *filename;
   filename = gtk_file_selection_get_filename(GTK_FILE_SELECTION(file_select_box));