Looking at the WMD editor tooltips, I see that Ctrl+Q is supposed to create a blockquote:
"Blockquote <blockquote> Ctrl+Q"
In the German keyboard layout, the @ and Q share one key, you would press ALT-GR+Q or the equivalent (as far as keycodes go) CTRL+ALT+Q to get an @.
You can probably see where this leads: Every time I want to type an @ I get:
on a new line. Doing many XSLT questions I need the @ quite often. Either I type all the code in an external editor, or I need to copy-paste a single @ off some other place around the browser. Every. time.
This annoys the hell out of me. I think checking the CRTL-Q shortcut for the state of the ALT key (must not be depressed) would fix this.