Information and error reporting

We have decided to use gtkinfobar as a main reporting tool.
Possible location is above notebook and below toolbar.
It will display the important current information or errors which were occured.
Probably we should add a 'close' button inside the gtkinfobar to allow to user hide it.

In conclusion the method is: when we have something which is needed to be shown to user, we show to him gtkinfobar with message.