code: function WidgetSliderGUI() {
          this.addOutput("", "number");
          this.properties = {
              value: 0.5,
              min: 0,
              max: 1,
              text: "V"
          };
          var that = this;
          this.size = [140, 40];
          this.slider = this.addWidget(
              "slider",
              "V",
              this.properties.value,
              function(v) {
                  that.properties.value = v;
              },
              this.properties
          );
          this.widgets_up = true;
      }
docs: Show value inside the debug console