Dual monitor support broken since 12 March - second monitor acts as single display

[Dave Hatton <mail davehatton it>]

Since the 12th of March I notice the following behaviour for my dual 
monitor set-up

1. In Activities the column "screen" layout only shows a single display. 
It previously showed two displays.
2. If I swap workspace using ctrl-alt- arrowkey the lefthand screen 
switches but the right hand display remains the same.
3. The options when right clicking the title bar of a window are 
different between windows on the left display and the right display. The 
left includes new options like "move to workspace down"

Does anyone else see this new behaviour?