This issue was incorrectly closed as resolved here:
https://mojang.atlassian.net/browse/MC-25967
This issue is not resolved and is not related to the issue sited on the previous post. This is a new 1.6.2 problem on OS X where pressing backspace in the chat deletes an entire word rather than a single character. It always jumps back to the previous space.
Still a duplicate of MC-3643.
Delete whole word: CTRL is stuck, delete whole line: SHIFT is stuck.