If you have installed the XFCE desktop environment in some other edition of Linux Mint, you might face a strange bug. The Network Manager applet is running and works properly, however, its tray icon is missing and won't allow you to access the app settings. Here is a quick fix to resolve the issue.
After a short delay, both, Linux Mint 17.3 XFCE edition and the corresponding KDE based branch have left the beta stage and are now available along with MATE and Cinnamon editions. XFCE is known as a lightweight yet powerful alternative to the MATE desktop environment. KDE offers a rich desktop experience for the end user providing a wide range of features and customization options.