Well, i'm currently deveoping a GUI for the MI0283QT2
this GUI uses buttons, switches, tabs, radiobuttons, checkboxes, textboxes, sliders and a statusbar to make GUI-handling suuuper easy
it won't be long until i release a first version of it(when i get the tab delete and radiobutton delete functions working).
If you would select another displyay it probably won't be hard to edit the lib to your needs, and to make it fit with the lib of your screen.
I'm curious how you are getting around the huge memory limitations for a full fledged gui on arduinos? With the Mega2560 it's not as bad but with a Mega328 it's horrible. I did something similar and developed a gui interface for a touch screen I have, and I could only load 20ish controls on the screen before I started having memory problems when combined with the program to use the gui library as well as the other libraries my program needed. That was even after minimizing memory impact by setting everything I could to byte types. I don't remember everything that I was storing but it was basic gui components like color,x,y,height,width etc. The bigger memory hits where the caption / labels 1 byte per character! 2Kb of ram on the mega328 is not very much to work with.