I know you have this new GUI for 'extended mode'.
However, with all that room you still need to have 4 different pages to display all that once used to fit into one page.
As you now have 4 sub-pages, and you can resize the app, I think you could put each of the single 'extended mode' pages underneath the wooden strip between the keys and the control panel, instead of that huge pop up. Then, the control panel stays in place and the keyboard would spring down slightly, instead of the control panel jumping wildly down, out of the window.
You could also put state indicators on the wood panel that show if effects, mod, motion, arp are enabled.
It would make it all so much neater.