How can I quote all text in a GMail reply, not just selected text?
Just to provide some background: Right now, it doesn't seem like you can turn this feature off.
There used to be a labs feature to turn "quote selected text" on. Very recently (mid-November '12) they turned it on by default, without providing a way to disable. I haven't been able to find any official mention of it, only comments from others who have noticed the change and miss the old way.
Apparently you can't (thanks Al Everett in comments above.)