As demonstrated in the OSGi screencast, TornadoFX let's a bundle export a View to other bundles by calling this function:

activator.registerView(MyView::class, "discriminator")

Under the covers, this implements an interface called ViewProvider and calls BundleContext#registerService with that implementation.

interface ViewProvider {
    fun getView(): UIComponent
    val discriminator: Any?
}

Here is the actual registerView function:

fun BundleContext.registerView(viewType: KClass<out UIComponent>, discriminator: Any? = null) {
    val provider = object : ViewProvider {
        override fun getView() = find(viewType)
        override val discriminator = discriminator
    }
    registerService(ViewProvider::class.java, provider, Hashtable<String, String>())
}

TornadoFX hides the need to implement this interface, but doesn't force you to abandon DS - you might just as well implement the interface manually. The choice is entirely up to the user, but you actually write less code by using the registerView extension function, and you don't need the extra build step so I suspect TornadoFX users will prefer the explicit way demonstrated in the screencast.

Granted, I'm no OSGi expert, and any input is greatly appreciated.