as a heads-up for those running MATE from testing. i suggest avoiding this upgrade for the moment.
it left my previously defined desktops mostly missing, many things weren't loading or reloading correctly, etc. so i downgraded to previous version and put mate-panel on hold. this was the list of packages and versions (i suggest not removing the previous versions from your cache until you don't need them any longer). ----- The following packages have been kept back: gir1.2-matepanelapplet-4.0 (1.27.0-1 => 1.27.1-1) libmate-panel-applet-4-1 (1.27.0-1 => 1.27.1-1) libmate-panel-applet-dev (1.27.0-1 => 1.27.1-1) mate-panel (1.27.0-1 => 1.27.1-1) mate-panel-common (1.27.0-1 => 1.27.1-1) 0 upgraded, 0 newly installed, 0 to remove and 5 not upgraded. ----- songbird