In the past version of Firefox you could define short-cuts for search engines. (by clicking on the black small arrow/triangle) and then "Manage Search Engines" - then you could define short-cuts)
This allowed typing the short-cut character followed by a space and then the search phrase in the address bar.
With the update to Firefox version 34 the option to define a short-cut is gone. Old short-cuts defined in previous version are working though.
So how can you define short-cuts for search engines in Firefox 34 (and later)?
I noticed this change today (2014-12-18) in the standards release version 34 and developer edition 36.0a2. I wonder why they changed it in both versions and how to define short-cuts from now on.