The new GUI is here.
First off is the new toolpane.
The buttons are pretty small, but they're easy to click at. The picture below shows them in detail, with their paths in orange.
As in vanilla, clicking on a province opens the province window.
Here is a more detailed picture, with explanations in orange. Note that taxation doesn't show up properly in this picture, since I hadn't corrected that when it was taken. The country flag will also be adjusted to look more like it does in the preview from last Wednesday. Finally, I will also adjust the settlement entry, it's not functional atm.
As you can see, I'm using Roman-looking miniatures to represent province parameters. I have avoided using text, to save space and give the GUI a more gamey feeling. Don't worry, though, the numbers are explained in detail if you hover the mouse over them. I'm not sure if I have mentioned my social classes somewhere else, but here they are: nobles, townsfolk, peasants and slaves. Another very unique feature is the province number, which you can see between the toolpane buttons.
All questions are welcome. Cheers!