It's been a while now but I'm fairly certain the compendium used to have them. Their lack of inclusion feels like an oversight, especially considering that the UI actually leaves space for one but just doesn't include it. It's extremely important now that the page up/page down buttons don't even work instead. That seems like a bug and I've made a report, but who knows, maybe it's a feature. Regardless, adding scrollbars feels like a no-brainer.