reno/themes/unity_mate/config/titlebar_top.json

{ 
"align": {
    "left": [
        {
            "widget":"widgets.clientmenu",
            "client":true
        }
    ],
    "center": [
        {
            "draggable": true
        },
        {
            "builtin": "titlewidget",
            "client" : true,
            "options": {
                "align": "left"
            }
        }
    ],
    "right": [
        { "widget": "widgets.base.subpanel",
          "layout": {
                "list": [
                    {
                        "builtin": "minimizebutton",
                        "client": true
                    },
                    {
                        "builtin": "maximizedbutton",
                        "client": true
                    },
                    {
                        "builtin": "closebutton",
                        "client": true
                    }
                ]
          }
        }
    ]
}
}