User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:53.0) Gecko/20100101 Firefox/53.0 Build ID: 20170518000419 Steps to reproduce: to insert a link in an Email, for years ctrl-L was used. Actual results: when pressing ctrl-L - nothing happens (meaning, the shortcut isn't used for other purposes). Expected results: the link dialogue should have opened. This happens now when pressing ctrl-K, which makes no sense to me: L for LINK K for ...?
This is by design, per https://www.mozilla.org/en-US/thunderbird/52.0/releasenotes/