code: public void addFileToRecent(File xmlFile) {
          ArrayList<File> xmlFiles = GUISaveState.getInstance().getRecentFiles();
          if (!xmlFiles.contains(xmlFile)) {
              GUISaveState.getInstance().addRecentFile(xmlFile);
          }
          this.recentMenuCache.addRecentFile(xmlFile);
      }
docs: /*
  If the file already existed, its already in the preferences, as well as
  the recent projects menu items, only add it if they change the name,
  otherwise everything we're storing is still accurate since all we're
  storing is the location of the file.