middle click on title to lower window isn't working in Ubuntu 15.04

[Mondane]

After upgrading Ubuntu 14.10 to 15.04, the functionality to lower a window so the one behind it is shown, isn't working anymore. A window could be lowered with middle clicking on the title bar both maximized and in a window.

A workaround can be found here:

http://askubuntu.com/questions/613036/how-do-i-bring-back-the-lower-option-when-middle-clicking-on-the-title-bar-in

Running this:

dconf write /org/gnome/desktop/wm/preferences/action-middle-click-titlebar "'lower'"

should fix it.

My question, why is this behaviour missing.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Mondane (mondane-woodworker)]

Just noticed that, with the workaround, when all windows are 'lowered', it isn't possible to cycle through them again. In the old behaviour, you could just keep middle clicking and the current window at the top would go to the back of the stack. This post, http://ubuntuforums.org/showthread.php?t=2142633&p=12635891#post12635891 , shows the following available values:

'toggle-shade'
'toggle-maximize'
'toggle-maximize-horizontally'
'toggle-maximize-vertically'
'minimize'
'none'
'lower'
'menu'

None of those give me a suggestion it would provide the functionality I require. Is this also a regression?