I’ve been discussing the layout of the forthcoming TB3 release on their mailing list recently.
Since I installed it on my new Asus 1008HA on top of the Ubuntu Karmic Alpha build I’m having a bit of an issue with the [relatively] huge size of the header panel for messages. According to a quick measurement in the Gimp, the header is using 137px of vertical space. Netbooks typically have a 1024×600px resolution, some are even smaller. 137px represents almost 23% of the available vertical space.

TB3 Classic View
Here’s a screenshot showing the typical layout I prefer clearly showing the space required by... read more