In this example, an instance of Uize.Widget.Bar.Slider.Plus is being wired up. This widget class wires up additional buttons for incrementing the value in either direction, and for setting the value to either extreme of the slider's range. Notice how the appropriate buttons become disabled when you're at either extreme of the slider's range. This is true of both using the buttons to change the value and dragging the slider's knob. If you're dragging the knob, then hitting either of the extreme's of the range will disable buttons appropriately.