Just a FYI about this app:
The list it provides includes arp cache entries. This is a bad idea, because it will show no longer available devices. If you use this app, clear the arp cache before (sudo arp -a -d) "scanning". It gets even worse, if you did a broadcast ping before.. Also lacks the possibility to chose the interface to scan. If you have several interfaces up (incl. VPN and such), it's kinda random which interface the apps scans.
So, well, a nice entry-level tool to make a fast scan, but beware of ghostly arp-entries.