Comment 10 for bug 753269

I had a look at the libwnck library to see when the 'workspace-changed' signal is emitted. The wnck library checks whether the atom _NET_WM_DESKTOP has changed. The description of that atom is here:

http://standards.freedesktop.org/wm-spec/1.3/ar01s05.html

"Cardinal to determine the desktop the window is in (or wants to be) starting with 0 for the first desktop. A Client MAY choose not to set this property, in which case the Window Manager SHOULD place it as it wishes."

It looks like it doesn't mean that the workspace id has changed, it just means that the window is in the process of moving to a new desktop. The signal might be better named 'workspace-changing'. I think the unity-2d code is correct to make the assumption that the window may or may not have moved. I couldn't see any other signal which was emitted once the window had moved.