Task Bar = Panel
My panels don't look anything like yours when I open something. The upper bar just has launchers and the standard running apps. The side bar now shows 'launched' apps, the workspace select button, and the trash bin.
I was able, stumbling around, to restore the bars and my favorite icons (like Network, Clock, Date, etc). Had to use a Terminal command, but got things back. Then I began to edit the 'Properties' to add the things I wanted. I found that the ONLY way I could get Launched apps to appear in the left side bar when I opened an app was to open Mate Tweak, Panel, then select the 'Familiar' theme. That seems to be the only theme that shows launched apps (I didn't try them all, just a bunch of them).
Then I add the few other items I want, like the Printer control.
Another bug I found was when I rgt click on a panel and select Properties, then changed the background to blue? It blew away the main Mate app launcher. The one that shows 'Places' and 'Apps' in a drop down menu. Had to go search for that to restore it by using the +Add to Panel command. That's all changing color blew away though...all the other icons, like Clipboard, Network, Speaker, Date/Time, then the shutdown launcher...those all stayed. That's why I think it's another bug in Mate Tweak.
Anyway, thanks for reading the post but I got it all figured out now...sort of. Until I forget it all again.