Mobile and DesktopOnlyPlaceholder
These are used to wrap content or controls that should only be visibe on either desktop or mobile. They can also be used in the head section of a page to render/not render JS/CSS resource link tags.
<waf:DesktopOnlyPlaceholder runat="server">
This is only rendered on a desktop
</waf:DesktopOnlyPlaceholder>
Page markup
<waf:MobileOnlyPlaceholder runat="server">
This is only rendered on a mobile
</waf:MobileOnlyPlaceholder>
The Mobile Desktop Toggle Button
The control WAF.Presentation.Web.MobileDesktopToggleButton is used to show a link to override the automatic desktop or mobile view.
The image below shows how the BBC homepage use the same type of desktop/mobile switch.
Properties
Override SwitchToMobileText and SwitchToDesktopText to set the default text. The links can of course be styled as you like using CSS.