As apparently my mail to the mod list was ignored...
Basically the 'code' blocks are utterly broken on IE10 : instead of resulting in a formatted box of text it is reduced to a single line which scrolls off to the right.
The source blocks, as above, work fine but given that 'code' is what the button on the editor produces this isn't very helpful.
So, I ask again; is this known? Is it going to be fixed? If so when?