I've got xfwm 4.11.1.  I can't tell which program is being raised to the top when using alt+tab. When I alt+tab, I see a "middle strip" of program icons, but they don't differentiate various terminals or windows of various programs.  I can't predict which terminal I'm going to get when I let go of the tab key.  

I found the XFCE4 window manager tweak where it will highlight the outside frame of the window to be raised. That highlights the shape, but doesn't raise the content of the window itself. I can tell the shape of the thing that will be brought to the top, but I can't tell what is in that box. 

Do you see it too?  Open 6 terminals, then Firefox, and maybe the Gimp. alt+tab will let you change, but you've got no idea which terminal you are changing into.

In WindowMaker, there's a setting "circulate raise" so that windows come to the top as you hit alt+tab, you can tell what you are getting. xfwm4 does not raise windows, and it is really tough to tell what you are getting.  It shows the same icon for all of the terminals that are open. The outlines of the window frames are highlighted, but the windows themselves don't rise, I can't tell what I'm getting.   

The old window managers often had this issue, but I've not seen it for quite a while, since 2005, maybe.  I wondered if window compositing is failing, so xfwm4 is trying to raise the windows, but it can't, and yet it can draw the electric edge around the window to be raised.