how, or where are instruction on what ‘Indicator Applet Complete’ is, where to find it, and how does one "add" it?
Days, into weeks, just to figure it out and still can't find some o the 'icons' or apps, or sudo thingies or what-evers, just to connect to Windows. Arrgggg!!!
I just want the Mate to drop files on the Windows folder somewhere, anywhere.
Thanks,
~i~
Right click the Panel, and choose Add to Panel. In the list that shows up look for 'Indicator Applet Complete' and add it, then move it to where on the panel you want it.
I'm catching up on some old stuff. FYI, my problem was (probably still is),. ignorance. Dum-dum here installed Ubuntu - and should have installed Ubuntu MATE. Once I reinstall but with MATE this time, it was like a a bright beautiful sunrise. 
~i~
Thanks SRG, your tip about resetting the panel, my hiding icon such wifi already back to my panel. Your tips work for me..