Module button 

Button — a clickable button with hover, pressed, and focus states.

Composition

Button is fully compositional: it always has exactly one child widget, a Label, which is responsible for rendering the button’s text. The [paint_subtree] machinery handles the Label automatically after Button::paint draws the background.

Button (background + focus ring)
  └── Label (text, tight bounds, centred within button)

Label::layout returns tight text bounds. Button::layout centres the label within the button area. Because Label::hit_test returns false, the Label is invisible to the hit-test and event-routing system; the Button retains full ownership of focus and click events.

Structs

Button

A clickable button.

ButtonTheme

A theme for Button visual states.