The notification area is the system tray area on the bottom-right of your screen. When many icons clog up this area and some of them are not so active but sit there doing nothing, then the notification area cleanup collapses and hides those icons and shows the notification chevron. Clicking on the notification chevron you can see the collapsed icons again. You can disable this notification area cleanup if you want. Here is how :
- Press the key combination Windows Key + R to open the Run dialog. Type gpedit.msc in the Run dialog and press Enter.
- In the Group Policies Editor, navigate to User Configuration → Administrative Templates → Start Menu and Taskbar in the left side treeview.
- In the right hand side pane, you will find a value Turn off notification area cleanup. Double click on it. Choose Enabled and click OK to save the settings and close the dialog.