I just suggested this on Reddit and was directed here. I wouldn't mind something like how Untangle does it with current IPs on the right and all static IP's on the left in columns and having the whole range of IP's visible. I love the functionality of the DHCP server but dislike the Web GUI for it.
A screenshot would be appreciated. We want to make the UI as clear as possible, however, our time is severely limited and, when there are no external contributions, it clearly helps if we'd know exactly how something should look like before trying a change like this.
For what? Sure, an unauthorized device will not get an IP, however, you can still get access to everything with a static address configuration. If you are looking for such a level of protection, the DHCP server seems to be the wrong place to look. It will only give a misleading feeling of security when circumventing is very easy and straightforward. You should instead use a router that is able to to MAC-filtering on its ports to achieve what you are looking for.