/usr/share/mate-panel/ui/mate-window-picker-applet-menu.xml is in mate-netbook 1.8.1-4+deb8u1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | <menuitem name="PreferencesItem" action="MenuPrefs" />
<menuitem name="About Item" action="MenuAbout" />
|