Group -> Left mouse -> Compiz Scale Windows doesn't work right

[SwanS]

The behaviour of "Group button -> Left mouse button -> Compiz Scale Windows" is not the expected, so replicating the Unity's style is not possible.

Left click over the group button, when there is no a window open, does nothing. Launching the application would be the expected action.

If there is only one window open in the current workspace and other one or more in another workspace, the focus moves to the last open window, changing of workspace. Focusing in the window of the current workspace would be the expected action.