Boxes out of nowhere in IRC?

[Tuc at T-B-O-H.NET]

Hi,

	Running IRC, have a room window up. If I click on a user,
then click on the bar under the box where the font/reset font/insert
is, I get a mysterious box open up in that bar. If I type, it tries
to match up the username. 

	Is this normal/documented?

			Thanks, Tuc