Does this glitch dealing with @username bother anyone else?

I frequently edit, back up and retype when I write posts. If I do this, the @username feature breaks and I can’t use it anymore. I know I can just type out the name myself, but sometimes if the name is long or I have trouble spelling it correctly, has spaces or nonstandard capitalization, the @username feature doesn’t work.

I didn’t write this just to whine. I want to know if there are any Firefox scripts or fixes so I can help myself. I’d like it to be added on a to-do list to fix. I love the @username feature. But my typing sucks and I need help keeping it working.