It works like a tooltip. When you move the mouse over it, the buttons appear, and you can scroll in it, or open it in a dedicated window. I wouldn't mind a shortcut based solution, though, either.

Sure the tooltip doesn't need to include the whole message, when that is too long; having a button in that tooltip that actually displays the whole thing in that case would be great, though (simlar to how Eclipse handles documentation for methods).

That being said, I rarely come across messages that long, and it's not fair to punish everyone for those who cannot contain themselves :-)

Yes, and please add the full message to the commit's tool tip while you're at it :-)