Why do you need to close the active window to access a log file? You can access them through ALT+O > IRC > Logging > [View Logs].
Alternatively, type //run $logdir and find the file there, double click, and open.
True to say that the file won't update on-screen whilst the file is open, but you can access it whilst the channel window/query window is open - unless a script is preventing it.
Regards,
