Additional primitives/widgets

[bugadani]

• [x] Scroll[Listener?] (#17) Reacts to pointer and scroll events, translates child widgets along the set axis. Sets clipping rectangle. Scroll offset should be r/w Optional over-scroll handlers?
• [x] CheckBox, RadioButton (#21)
• [x] Slider, scrollbar (#27) Multiple types: point selector, interval selector, fixed width interval selector (i.e. scrollbar)
• [x] Text input (#50) This should probably be an even listener similar to button - set state (based on selection) and have no inherent graphics. Alternative is a complex textbox with cursor. Moving the cursor using pointer events will be fun. e-g backend implements using embedded-text, https://github.com/embedded-graphics/embedded-text/issues/60 could help.
• [x] Tabs/pages - kinda-sorta possible using Visibility and Toggle buttons
• [x] Layer container Has implications on rendering
• [ ] Canvas widget - draw embedded-graphics primitives

Longer term possibilities:

• [ ] Switch Not quite a Toggle because it might need to handle drag events to be fancy. Figure out how to bubble up toggle requests?
• [ ] Templated list This might be a tricky one.
• [ ] Image
• [ ] Cascading menu
• [ ] Window (resizeable, movable - closable?)
• [ ] Resizeable panels (draggable separator)