Slider

ui.Slider creates a slider setting a *float64 between a low and a high value: dragging the knob, or a press on the track, sets it, as do the arrows, Home and End while it has the keyboard focus. Changed reports a new value.

ui.Slider(c, &app.volume, 0, 100).Label("Volume")

Steps

ui.StepSlider snaps the value to the low value and multiples of a step from it, with a tick mark at each, as AppKit's sliders with tick marks: dragging snaps to them, and the arrows step by step.

ui.StepSlider(c, &app.quality, 0, 100, 25).Label("Quality")

For a low and a high value at once, as a price range, use a range slider; for exact numbers, a number input or a stepper.

Without a look

ui.SliderBase is a slider without a look: dragging across its content box, within its padding, sets the value. Draw its track and thumb where (value-lo)/(hi-lo) puts them, and pad it by half the thumb's width to keep the thumb inside it:

s := ui.SliderBase(c, &app.volume, 0, 100).Height(24).PaddingX(12)
s.Draw(func(p *ui.Painter, r ui.Rect) {
	x := r.X + 12 + (r.W-24)*float32(app.volume/100)
	p.Fill(ui.Rect{X: r.X + 12, Y: r.Y + 10, W: r.W - 24, H: 4}, gray, 2)
	p.Fill(ui.Rect{X: x - 12, Y: r.Y, W: 24, H: 24}, blue, 12)
})

See custom widgets.

Accessibility

Assistive technology sees a slider of its range and value, named by its Label, which it increments and decrements as the arrows do.