You might activate the "Pause" option in the window when examining the window contents.

I don't know if this is a bug but it surely is annoying and I don't recall seeing it in many years of using Mercury.

If I am scrolled up in the core process's window, examining the recent history, then when poll-time comes around, that window automatically scrolls to the bottom.  There is no activity and no entry is made; it just scrolls to the bottom, spoiling my trying to see what happened earlier.  This doesn't happen in MercuryE's window.
 

If you do have ready or pending jobs in the queue then I imagine there is activity (determining if to resend) even if nothing is logged. But I agree the log window shouldn't scroll unless something is actually written.

[quote user="Peter Strömblad"]If you do have ready or pending jobs in the queue then I imagine there is activity (determining if to resend) even if nothing is logged. But I agree the log window shouldn't scroll unless something is actually written.[/quote]

There was nothing in the queue at the time.  It continued as I said for hours.  I restarted Mercury.  The log window has enough in it to require scrolling and, so far, the problem hasn't returned.  Perhaps it will return when the log gets enough text in it.  If it does, I'll be back.