How to show system messages

[Carlos Toledo <sarek22 casal upc es>]

Hello, i want to ask you more than a problem with gtk, a problem with C.
I want to do a messages console that shows the file /var/log/messages but
I have the problem that this file grows with all messages and when I have
read it, there is more information on this file. How can I do to know when
is new information whithout read the file all time or looking the size? 

Thanks for your help 
(sorry for my horrible english)