The old editing behaviors are back in 4841-4853: entity flinging, entities snapping back and forth scores of meters on the tiniest amount of mouse pointer movement, cannot often select an entity at all. I just flung half my domain to smithereens, so now restoring from backups.
I stopped all scripts, then started defaults.js in case there was a script conflict. If there is conflict, then it is inside defaults.js
I tried going back to a known working version 2831 but of course that no longer works because of the big packet-interface change. so, taking a break from HF.