This appears to have been caused by my changing a preference setting from "normal" to "extra" in:
Preferences -> Appearance -> Visual effects
I have changed the setting back to "normal" will post if I see any more garbled displays.
This appears to have been caused by my changing a preference setting from "normal" to "extra" in:
Preferences -> Appearance -> Visual effects
I have changed the setting back to "normal" will post if I see any more garbled displays.