I don't know if it's something to do with the plug-ins etc that have been disabled to try to get away from the malware warnings, but the "strikethrough" option has vanished from the basic toolbar. We can now only get to it by going "Advanced" which a) is a bit of a faff and b) I keep forgetting to do until I'm editing a post and suddenly realise I need to strike something out. I had taken to putting the code in manually but on one post earlier I mixed a / up with a ] and the code appeared in the final post, unnoticed by me but noticed by a learner.
Any chance of getting it back on the basic toolbar? Everything else needed for basic editing is still there.