Intermittent strange text artifacts in Free Flow editor -- what is it?

Intermittent strange text artifacts in Free Flow editor -- what is it?

I occasionally get very odd text artifacts in the free-flow editor (image below).  I've seen this effect in both Firefox 3.66 (Mac) and Safari (latest version), and I think I even saw it in Chrome (Mac) one day when trying to escape the effects.

For no clear reason, the editor sudden displays a shadowy replica of the code in light gray shifted down a few lines.  It creates problems with cursor placement and readability.  This effect is intermittent, not all the time.  But I've seen it almost daily.

Has anyone seen this too?

Example >>


Greg Malone
Santa Fe, New Mexico, US