Even if you get rid of %t from -rmsg, joe still writes to the screen once a minute, waking up terminals which notify about activity (such as xfce-terminal). This way, every tab that has an editor open flares up every minute.
(You might also want to drop %t by default — every desktop environment already has a clock on the screen.)
We did drop %t by default with JOE keybinding. I see we still have it for jstar, this needs to be fixed.
That's kind of funny with xfce-terminal, I'll have to try it. It's true that there is a background redraw every second, I'll have to rethink this.