refused connection from client

[Usuário do Sistema]

Hello Everyone,

I have an application ( fwbuilder  to manager my firewall ) that needs
an Xserver to run.

so...as I'm using the ubuntu I make it as target for my fwbuilder.
until some days ago it's worked  but now nothing. I've done some
changes in my Ubuntu desktop and I think is missing something.

My question is for Xserver ( installed in my ubuntu desktop ) receives
any connection from other clients what is necessary ? what is the
libarys ??

thank ??