Comment 2 for bug 552539

So the current behaviour is fairly deliberate - since the grouping feature relies on colour and the grouping menu is only accessible from the titlebar, I wanted to leave a tiny hint of the colour and a very small clickable area.
Previous iterations had a 2px border around the whole terminal and no access to the grouping menu, which seemed to be much worse all round.

I'd really like to find a way to not hide information from people about the grouping - I think it's important to know if a terminal is going to receive/send keystrokes to other terminals, but I'm very willing to discuss how we can achieve this in a way that keeps the no-titlebar crowd happy :)