A component needs to be called in context of a controller (with included Matestack::Ui::Core::Helper), which is true when you're calling components of Rails views or on Matestack Pages (which are themselves called by a controller normally).
When calling a component in isolation (which is possible), the view helpers might not work properly!
It's currently not possible to use view helpers requiring a block, such as the form_for. We're working on supporting them soon!
Custom HTML Tags
If you want to use HTML tags which are not supported by Matestack's rendering mechanism by default, you can call ActionView's tag helper manually: