Back in gnome2 times, I used to have maximus (or appropriate compiz setting) + window picker applet. For those who don't know, these 2 little programs mainly do 2 things:
- remove decorations for maximized windows
- add a closing button to the window list's icons
(example of what it can looks like)
I'd love to see that reimplemented in some way in cinnamon, it's a great way to save some useful pixels.