@Dan It’s not growing so much. The RepRap Graphic Smart Display Controller Board (https://www.amazon.co.uk/Redrex-Graphic-Display-Controller-Printer/dp/B01LO20XGS/ref=sr_1_4?ie=UTF8&qid=1552836185&sr=8-4&keywords=reprap+display) is in millions 3D-Printer and it is the cheapest and greatest display. China produces this display 20 millions a year for makers, 3d-printers, cnc-machines.
Is it possible that you copy code from marlin-firmware?